I wish I slept with a girl I had mutual attraction with years ago

I've known her since I was ten and she's 5 years younger than me. We would go on the same vacation each year with my family (her dad is my dads half brother). She was like a little sister to me and I had been there since she learned basically everything. <br><br>We played a game of truth or dare at her birthday party. We went together in the woods (no one was around). I was 17 and she was 15 when I did it. I gave oral to her and she gave me oral back. But that was it as I decided not to do it further and I felt guilty for doing it. I even kissed her on the cheek once and when she came to our home (after a few months) and slept in my bed I felt uncomfortable (because of the feelings I was developing for her).<br><br>I know it was sexual abuse but in my defense I was 17 and dumb as bricks. I was ashamed and I distanced myself from her after that (she would send me letters and I wouldn't reply to them). I slept in a tent the next year at the vacation and I even slept at a hotel for a night when we were at a family visit at their place (after we had an argument). I was in my own world at the time and I felt like I had made a huge mistake. I still hid my feelings but I did it in a way where I felt like I was punishing her. <br><br>I only found out now (thanks to her husband) that she was in love with me and that she gave up on girls because of me. I was really stupid and now I regret it. It feels like I killed a future "us" and a future with a girl I could have been with. I know she's married now but I still wish that I could have explored that relationship 10 years ago.