I found nudes of a girl I like

For the longest time I've had a crush on my sister's friend. She's younger than me but not by much, she's always been very friendly but in any case nothing ever happened because we were both in a relationship. Some time ago she moved, so we don't live near each other anymore. The sexual attraction I had for her was insane, every time we were together as a group with my sister and her friends I couldn't help but undress her with my eyes. As a premise, I have to say that my sister always had a passion for photography, even though she never did anything professionally. Last year I was fixing her PC and while doing a backup of her stuff curiosity got the better of me. I saw a folder with this girl's name and clicked on it... Inside there were a few photoshoots of her in suggestive poses, half naked and even topless in some pics. I dropped everything I was doing and immediately started jerking off. I was completely stunned, I never ever thought I'd see her like that... I came twice and had the best wank session of my entire life. Now when I go on her instagram and look at her pics I always imagine her naked. This kinda ruined me because now I need more... In all this my sister still has no idea, or at least we never talked about it and I doubt we ever will.