My bestfriend has been ruining my relationships for 9 years

I found out my best friend has been secretly ruining every relationship I’ve had for almost 9 years, and I think she’s done way more than just send messages I honestly still feel sick writing this because if I hadn’t caught her in one stupid mistake, I probably would’ve gone my whole life thinking I was just unlucky in love. Sorry for the long read. I’m 27F. My best friend is also 27F. We’ve been friends since middle school, and I mean *best* friends. Sleepovers, family vacations, birthdays, breakups, everything. She’s the kind of friend my mom used to call her “my second daughter.” She was around for all of my big life moments. She knew every guy I ever dated, every insecurity I had, every password I was dumb enough to share when we were younger, everything. And for years, every serious relationship I got into would eventually fall apart in the same weird way. At first things would be good. The guy would be affectionate, consistent, and genuinely seem into me. Then out of nowhere, every single one of them would get distant. Some would become suspicious and weird. Some would accuse me of things that made no sense. A couple of them straight up ghosted me after months of dating. Every time I asked what changed, I would get some vague answer like, “I heard some things,” or “I don’t know if I can trust you,” or “there’s stuff about you I didn’t know.” I always thought I just had horrible taste in men. One ex accused me of flirting with his cousin at a cookout. I never even spoke to his cousin outside of saying hello. Another said somebody told him I lied about being pregnant in high school to keep a boyfriend from leaving me. Completely false. Another said he’d heard I had an STD and was “careless” about telling people. Again, false. It was always something humiliating, random, and just believable enough to make them look at me differently. I spent years defending myself against things I didn’t even understand. I cried over this. I went to therapy over this. I seriously thought something about me just made people stop trusting me. Then I started seeing someone new a little over a month ago. He’s honestly the first guy in a long time that made me feel calm. No games, no weird energy, just normal. Things were going really well. We weren’t official-official yet, but it was heading there. Then one night we were out eating and he got quiet. He kept looking at me weird. Finally he asked me, “Why didn’t you tell me you cheated on your ex?” My stomach DROPPED. I told him I have never cheated on anyone in my life. Ever. He looked uncomfortable and showed me screenshots from a random Instagram account that had messaged him. The account claimed to be a girl who “knew me personally” and was trying to “warn him.” The messages said I was manipulative, that I cheated in every relationship, that I had stolen money from an ex, that I faked a pregnancy scare once to keep a guy from leaving, and that one of my exes had to get tested after being with me because I’d “been around.” I literally felt my face get hot reading it. It was so specific and so nasty that it had to be someone who knew me. Not just knew me, but knew exactly what would embarrass me the most. I asked him why he believed it. He said he didn’t fully believe it, but some of the details sounded so personal that it scared him. I don’t even blame him for that, which somehow makes it worse. But something about the wording in the messages bothered me. I couldn’t place it at first, but the tone felt familiar. There were little phrases in it that sounded like *her*. Not enough that I could accuse her, but enough that a little alarm went off in my head. So I decided to test her. The next day I called my best friend and casually told her that the guy I’m seeing surprised me with a bracelet that cost almost $4,000. This was a complete lie. There is no bracelet. There is no $4,000. I picked something super specific on purpose because I wanted to see if it would come back to me. Three hours later, the fake account messaged him again. The message said, “Ask her where she really got that $4,000 bracelet. Men always fall for her innocent act.” I think I actually stopped breathing when he sent me the screenshot. That was the moment I knew. But even then, I still hoped I was wrong somehow, because I genuinely could not wrap my head around my best friend doing this to me. He helped me try to recover the account through the “forgot password” process. We typed in the username and got the partial recovery info. The recovery phone number ended in the same last two digits as my best friend’s number. I still didn’t confront her immediately. I wanted more. I started thinking back over years of weird things she’d done that I brushed off. Times she “joked” that men always picked me first. Times she would go quiet if I talked too much about a boyfriend. Times she’d ask oddly detailed questions about where I was with someone, whether we had arguments, if he knew certain things about me. She always framed it like concern. Then I remembered something even worse. A few years ago, one of my exes randomly changed his mind about moving in with me after we’d been planning it for months. At the time, he said he found out some things about me that made him question my honesty. He never told me what those things were. Around that same time, my best friend had “helped” me by offering to organize some of my photos and contacts because my phone was glitching. Now I’m almost positive she was going through my stuff. I confronted her two days later. At first she denied everything. She cried. She swore on her mother’s life. She said I was insane for even thinking that. Then I told her about the fake bracelet. Her whole face changed. I can’t even explain it. She just kind of… deflated. Then she admitted it. Not just the new messages. Alllllll of it. She said she had been secretly messaging, calling, or “warning” almost every serious guy I’ve been with since we were 18. We are 27 now. Almost nine years. Nine years of this girl sitting in my face, hugging me after breakups she CAUSED, bringing me food while I cried over men she sabotaged, telling me I deserved better while actively making sure I never had a chance to find better. And it gets worse. She said in the beginning, she would only do it if she felt like the relationship was “moving too fast.” But over time it became a habit. Sometimes she made fake accounts. Sometimes she used texting apps. Once, she admitted she pretended to be a former coworker of mine and emailed one of my exes to “warn” him that I was “unstable.” Another time, she sent a guy screenshots of old messages between me and someone else out of context to make it look like I was entertaining multiple men. One of the most sickening parts is that she admitted she sometimes used real things I had told her in confidence and twisted them just enough to sound awful. So if I told her I had an argument with an ex? She turned it into me being “crazy and abusive.” If I told her I was late on my period once and scared? She turned it into me trapping men with fake pregnancy scares. If I told her an ex loaned me money once? She turned it into me scamming and stealing. She weaponized literally every vulnerable conversation we ever had. When I asked her why, she said every time I got into a relationship, she felt like I disappeared and she “stopped mattering.” I asked her why she didn’t just TELL me that. She said she tried to “drop hints,” but I never noticed, and after a while it made her angry how “easy” it seemed for me to get attention from men while she felt invisible. Then she said something that really made my skin crawl. She said, “At first I was just trying to slow things down. I didn’t mean for it to become this whole thing.” Then she admitted that with one ex in particular, she didn’t just message him. She met up with him. She told me it was only once and that nothing physical happened, but I don’t believe her. Apparently she told him she was “worried” about me and wanted to explain “what I’m really like.” She said he was confused and hurt and she “comforted” him. I wanted to throw up. So not only did she sabotage my relationships, but she inserted herself into at least one of them directly. When I asked if she had ever slept with any of my exes, she swore she hadn’t. But at this point I don’t know what to believe. The worst part is that after I confronted her, she started spiraling and blowing up my phone with messages. First it was apologies. Then long paragraphs about how she’s mentally unwell and needs help. Then she switched to saying she was scared of losing me and “didn’t know how to stop.” Then when I stopped answering, she started posting vague things online about being abandoned by someone she “would have died for.” A couple mutual friends already reached out asking why I’m being “so harsh” when she’s “obviously going through something.” I haven’t even told them everything yet because honestly it sounds insane. How do you explain to people that your best friend ran a nearly decade-long covert harassment campaign against your love life? I changed my passwords. I blocked her on everything. I told my current guy the full story and showed him all the screenshots. He was horrified. He’s been really supportive, but I’m also embarrassed beyond belief. I feel violated. I feel stupid. I feel like a huge chunk of my adult life was manipulated by someone I trusted more than almost anybody. Now I’m sitting here replaying every breakup I ever had and realizing there may have been a shadow version of my best friend standing behind all of them like some deranged producer. I genuinely don’t know how to trust anyone after this. And the worst confession of all is that a small part of me still misses the person I thought she was.