Wrestling with guilt about past mistakes

Hey all, I just need someone to tell me if I am a monster or not. I am currently 22, and when I was 18 I made probably the biggest mistake of my life. I have had a pregnancy fetish as long as I can remember, I do not know why or how, but it has always been with me. In march 2020, when the pandemic started, I was inside all the time either looking at porn or trying to sext women on omegle. Specifically pregnant women. One day, I met a 15 year old that was on omegle who said she was pregnant. I told her I was 18 and she didn't care. We exchanged snapchats and sexted a few times. About a month or two afterwards, I realized what I did was awful and I blocked her on everything. I have talked to my therapist and a priest about this and they both agreed that I need to let it go, but I just can't. I would love to be married and have kids one day but I feel that I have done such an awful thing that I cannot lead a good life going forward. I feel like I deserve to go to prison and no one knows how awful I really am.