Having a hard time forgiving my past... help?

Okay, so about 5 years ago when I had turned 18, I had lost my virginity and I was very serious about protection. I knew how important it was.

But a few months later I had become close with a group of people, I went to a few parties and got drunk.. I ended up having unprotected sex with 3 people. I don’t talk to that group of people anymore either. I felt so gross for such a long time and I still do to this day. I would get tested for months up until 2 years ago. Luckily I never contracted anything. But I can’t let it go. I know I wasn’t in the right state of mind, I know that wasn’t me. But I still let it happen. I feel like such a bad person. I have never done anything like that since, and I never plan too. What hurts is how disappointed my mom would be in me, because she always made it a point to make smart choices. Anyone have any similar feelings? Any advice? Thanks in advance