I think I accidentally SA’d my best friend. She says it’s fine but I feel mortified

Me and my long term friend have enjoyed sex on occasion but have always been respectful of our friendship and boundaries. She came over for a drink the other night and we ended up chatting and drinking till the morning. We decided to get more alcohol and were drinking through the day. We were being really flirty and I asked her if she wanted sex. She seemed down at first but changed her mind saying she didn’t want to have sex with someone if she didn’t if it wasn’t going anywhere else and she was holding out for someone she likes. I was obviously respectful of this. The night goes on and we are still being very flirty and a little touchy but it’s getting late and she should probably call a taxi as she has work in the morning and we’ve been awake for 30+ hours together. She never does call a taxi and we end up falling asleep next to each other on the couch. I wake up to the sound of her moaning and grinding her hips. I realise that my hand is on her crouch over her leggings (it wasn’t there when I fell asleep). I’m feeling really hazy at this point but decided to start gently rubbing my hand and she clearly got more excited. I move my hand into her underwear and she moves her leg up on my stomach and shifts her hips so I have a better position. I’m rubbing and fingering her and she is moaning very loudly and arching her back so I decided to move things further and shift her in a position where I could be on top. I take of her underwear and she lifts here hips up to help me do so. Before things go further she tells me ‘no’ so obviously I stop. She says sorry and I tell her she doesn’t have to apologise and I ask if she is okay. She tells me yeah and then asks me if we had had sex and what had happed. start feeling panicked and tell her that I have woken up with my hand on her crouch and thought we had escalated things. She doesn’t say anything and I tell her I’m sorry and would never purposely do everything to disrespect her boundaries. She says ‘it’s fine’. I go to throw up because I’m feeling completely overwhelmed and hazy from the drink and lack of sleep. I come back and she calls her taxi to pick her up in an hour and we go back to sleep for a bit. When we wake up she is clearly very frustrated and is borderline shouting at me that she can’t find her lighter. I ask her if she is okay and she says she is just confused but won’t say why. I tell her I’m so sorry if I’ve hurt her and I hope she will be okay. She says it’s okay and gives me a short hug and leaves. I message her shortly after to see if she got home safe and say sorry again. She responds the next day saying it’s all good and how she had a really fun time over the past couple of days. I am struggling to see how it is okay and just feel sick to my stomach that I could have disrespected her boundaries like that. We have a very strong bond and I hope she isn’t just playing it off for the sake of our friendship. I regret so badly that I didn’t check things were completely consensual but we’ve initiated sex in the same way several times before without issue so at the time I was sure she was encouraging my advances. At no point we either of us were black-out drunk. I’m not trying to make excuses, I know what I did was wrong. I don’t know what to do. It’s been eating at me for days and I feel like a truly terrible person.