I was SA as a kid and nobody knows

Currently I (17m) am in high school. Yesterday I was talking to a couple of friends and the conversation drifted towards sexual experiences (you know, typical high school bragging rights things like "Jessica gave me a handjob under the bleachers" and stuff like that) and it came to my turn. Now I'm not ugly by any means (6'3, 220 lbs.) But I wouldn't say I'm that attractive either. About 6 years ago I was talking to this girl named Bella (she was 14 at the time). At the time I had never had a girlfriend before and was nervous about how to go about things. So after a while of not making any moves she straight up just tells me over Snapchat that we're dating now. Now being a naive 11 year old (and this being a girl 3 years older than me) I just went along with it and was super excited. After school I would tell my parents I was going to the park to hang out with friends when I was actually going there to hang out with Bella and her friends. I wasn't really a bad kid so they never questioned anything other than how long I was going to stay for. One day I got to the park and it was just her without her friends there. I asked her where they were and she says that they couldn't come today but "we won't be needing them". I went along with it, as per usual and we started off just having fun at the park just as regular friends would. She says abruptly "I need to go to the bathroom" and starts trying to get me to come with her. I say "but that's the girls bathroom" and she just goes "just come on" in that sweet enticing voice that she made whenever she wanted me to do something. So I went with her and sheepishly entered the girls bathroom. There's nobody else in there and she instructs me to pull down my pants to which I hesitantly said "okay" since I was a dumb child. In the back of my mind I knew it was wrong but it was so enticing I couldn't say no. I can't go into detail here because my hands are shaking just writing this, plus it's about an 11 and 24 year old and that's just gross. But we end up going at it, with her instructing me at the start and when it was done, she just said bye and left me there. I went home and didn't know what to feel. I knew it was wrong but I liked it so much I thought it couldn't be wrong. So it happened over and over again for the next few weeks until she just ghosted me on everything and wouldn't even look at me. I cried and stopped eating for days and when my parents asked what was wrong I couldn't tell them because I knew they'd be mad at me. They sent me to therapy and I developed a crippling porn addiction that I just recently began to come out of. When I told my friends this story they weren't smiling and laughing like they were at all the rest of them and told me I needed some serious help. And only after that did I realize that she really f-ed me up. Im thinking about finally opening up to my parents about it and getting some proper counseling. God I fucking hate her.