I need advice please

(For reference im a 21 year old female in college)

I have an ex that I dated for a year. Let’s call him joe. Joe and I broke up last July and went essentially no contact for months. We didn’t start texting or anything again until December when we ran into each other at a function. During the time we were broken up I had sex with someone else. This is only the third person I’ve had sex with, and the other two were long term bfs (one being joe). Joe and I have talked a lot since then and are now working on getting back together, which I want badly bc I love him. I told joe that while we were separated that I went on a date and “did stuff” with another guy but I didn’t word for word say I had sex with him. I just still feel so guilty. I know I didn’t cheat on him but i just feel like if he knew he wouldn’t be able to stop thinking abt it. I feel like part of the guilt is bc deep down I knew I was still in love with my ex. And I even told him if he got with anyone else during our time apart I don’t want to know. I just cant stop beating myself up abt it. I also feel like some of this guilt stems from the fact I was raised very Southern Baptist and so I feel guilt from the fact I had sex with someone, esp someone I wasn’t dating bc I’ve never done that before. Are there any tips or a way to forgive myself ?