I have been single for like 6 months now and still beat myself over this shit 

I lose sleep over it, get anxiety, waste hours during the day on it sometimes, and just tired of letting this drag me down. I need some help or wisdom. 

There are good streaks where I forget about it but then seems to pop up, which I know is normal

I have a good heart and believe I am a good person so idk why I keep obsessing over this one thing

Anyways, anyone who takes time to read this I appreciate you and going to summarize basically what is causing me to feel like this. (keep in mind everyone makes mistakes) 

In college, I was getting to know this girl and eventually we hooked up one night. The next day or so, 2 of my buddies asked me if we had sex, which I revealed that we did and told them it was good but there was kind of an odd fishy smell.... which is what I regret and feel so bad about. I remember I told them that it wasn't a big deal though and I really like her so don't say anything or something along those lines and tried to just make it positive. ( I was in a strange time in my life where I was very secure in myself being alone and I think I had a vulnerable moment where I just spewed stuff off the top of my head with no filter and wasn't very smart with social skills because I spent the last 2 years with only engaging in mild partying or friends, I think I just had a douchebag moment with some fellow bros and thought it was cool or something). My only excuse really is that we weren't dating at the time, but we ended up falling madly in love and dating for 2 years and this whole situation was never a problem. I really loved the girl, I didn't know how much I would feel for her at the time and don't think I would ever do such a shitty thing like that if I knew. I helped her solve the issue with her OB/GYN and many appointments and frustrating long crying nights and what not. 

We broke up for other reasons, mainly because it was becoming one of the most toxic things ever had in life and lots of things happened (she did some pretty messed up things tbh, I know it's probably a good thing I have moved on and don't have her in my life anymore due to some of the stuff had to go through) 

But this one thing from years ago and before we even dated still sits with me in my mind and beats myself up in my self conscious. I think it is because I told her absolutely everything, but this is the one thing she doesn't really know about and I think it is because I randomly overthink that the 2 friends I told about this are thinking about it like I am or something, which is probably completely false and the least of their worries. 

I don't know why I let this get to me as I take it very seriously to treat it as a learning lesson to not disrespect someone's secrets like that again and know that isn't who I am. Also, she caused a lot of pain and hurt to myself as well so idk why I give it the time of day when she doesn't deserve me either from the betrayal's I caught her doing to me, manipulation, control, leading on, hitting me, and acting like I wasn't good enough for her or her friends a lot of the time.