It's so brave for you to reveal these things @waterbuggy . At 19 you are still developing physically. I know you are grown, and of course it would be criminal and an awfully destructive thing, as you are so painfully aware of, to hurt and betray a child, the way you were hurt and betrayed. You clearly feel you are doing something wrong...it does sound like a compulsion which you want help to overcome.
Please do find a therapist that you can trust to guide you with these painful issues. Please do not destroy yourself. You are still developing, and it could take a long time to resolve these issues, but the world will be a better place for your recovery.
There are lots of people happy to listen and not judge you. Don't be scared to ask for help. Feel free to PM me. Call Samaritans on 116 123 and they will only offer reassurances. You're never alone in this world