How do I cope with this?

I am a 15 year old freshman in highschool. Please keep in mind when reading this and giving advice that I am underage so that does change the situation drastically. So I have a friend who is my neighbor who I've been friends with since I was 5. He has an older brother who for the sake of privacy I will refer to as John. John is a senior in highschool, meaning he is currently 18 (3 ish years older than me). He often hung out with me and his little brother. When I was 9 ish and he was 12 ish he introduced me to sex. We began "experimenting" as most kids that age do. Without going into detail I will say that there was touching and oral sex involved. Since I didn't know any better and had no idea that what I was doing was wrong (not because it was with a guy, my parents are very accepting, but because I was a kid) this became a regular thing. I was too young to "finish" at the time but he wasn't, and it went that point as often as we could be alone together. We would sneak upstairs to his room and mess around for a bit, then come back downstairs and act like nothing had happened. At this point in writing this I am starting to realize that I left out an important detail. This whole process was silent, no talking. He just touched me and it felt good so I let him keep going. He is also physically a lot stronger so I couldn't have stopped him if I tried. Don't get me wrong, it wasn't rape, I would sometimes instigate it and touch him first, but only because I knew no better. I don't feel like I was raped, rather I feel that I was used and taken advantage of. For 4 years this continued until one really close call where his dad almost caught us. His Dad probably figured out what we were doing, although I don't know if he talked to John about it. That day he messaged me on Instagram and said "you need to stop the gay shit". This was the first time we ever really spoke about our sex, so it caught me off guard. Looking back now I realize that not only was he mad for what he had done, but now he was making me look like the bad guy. He was blaming me for being "gay" when he was the one that made me this way. I immediately stopped for a while from fear of being caught. I fell into depression, not because I missed him or anything, I never really had feelings for him I just messed around with him because I never really knew it was wrong. I felt depressed because I began questioning my sexuality and right around then my brother (now sister) came out as transgender. This was confusing enough in itself. I've dated girls, but now I find myself attracted to men and women too. I feel like this is my fault and I just don't know how to deal with this. I am in the closet still with my friends and family so talking to them is really not going to work. How do I cope with this and move on? How do I forget about someone who scarred me emotionally so much? Any help is appreciated.