First of all, I want to remind you of how strong you are for holding on because sexual abuse if one of the most difficult things to cope with.
Secondly, please don’t feel guilty or feel like you made a mistake; it was and it still continues to be their fault. You are a victim in this and you should not feel ashamed or guilty because it is in no way your fault. What they did to you is on them, that’s what they chose to do, it’s not something you decided for them. I may not know your story but I know that someone took advantage of you and it was not your choice.
I know that seeing as it was your first sexual experience you think that it was you who did something wrong but trust me you did nothing wrong. You should not let your first sexual experience define all the others that will come. I know that with this kind of trauma many people struggle with having relationships or being intimate with others and if you’re not ready to do that yet, don’t blame yourself and be proud of yourself for getting through what you got through or simply for being a survivor. Give yourself time. You are allowed to have relationships even after what happened, it was not something in your control and just because that person damaged you and how you think of relationships, doesn’t mean you won’t find someone who will try their best to make you feel comfortable with everything again and who I’ll listen and understand anything you say. Remember that you are strong and it is them who should be feeling guilty for forcing you and ruining your first experience.