Haunted by things that I did when I was younger

For starters, I'm a 16 year old girl. This stuff is really difficult for me to post and I'll most likely never be able to tell this to another person face to face, probably not even my therapist.
I guess that around 13 to 14 is the time when some girls learn about masturbation etc. When I was this age I did, but it was through doing stuff that was sort of masochistic, stuff like giving myself wedgies (I'm so unbearably ashamed) and things like that. I'd go on websites and get dares of things so do, always keeping safe and never giving out details but I got a bit of a kick out of it. Even at the time this felt so completely unconnected to the rest of myself, almost like a Jekyll and Hyde situation. It makes me sick to think about it, I can't even properly connect it to myself as I am now, almost like it was something I imagined.
I feel like these memories haunt me and that I've lost some sort of innocence and self respect that I can never get back. The whole thing has altered the way that I perceive myself and probably been the root of a lot of the self hatred that I feel.
I just want the memories not to be there, they make me feel dirty and very occasionally the knowledge that I'll never forget about it makes me want to kill myself.
Please help me.

Hello foolishness and welcome to the forum.

There are things in our past we never forget, true, but I think the emotions attached to these memories can fade over time. Time is healing. We all do things we regret in life and you were young. You still are. I think you can move past this and regain your self respect. You are more than just these incidents. Seriously, we all have things we look back on and think “What was I thinking?!?!” Live and learn, right? You are human and will make mistakes but I think you can move past this. You have your therapist to talk things out with, which is good, and I hope is helpful for you. I wish you the best.

*hugs* and take care.