real event / rocd

I slept with my ex while getting to know my now boyfriend. I started talked to my boyfriend 3 months ago and he asked me to be his girlfriend about 3 weeks in. I wasnt looking for anything but when I met him, something about him just stood out to me so of course I said yes. While talking to him though, I had no idea whether he was really really into me like I was to him. I didnt know him well enough to know his texting style or how he showed he cared. One day he cancelled plans on me because he said he had forgotten he had made plans with his friends first. In the moment I took it pretty hard because I was like oh maybe I should lean back a little bit, maybe he didn’t really wanna hang out. He had been taking hours to text back that day so once he cancelled plans for some reason it triggered something in me like “oh here we go again”. Little did I know he had genuinely forgot the plans he made but I dont know, at that point i was just so in my head. I had already showered and was going to start getting ready so i figured I would still go out. I went to get drinks and long story short I slept with my ex. This was before we made things official. The guilt was eating me alive after he asked me to be his girlfriend. I know i didn’t cheat but it feels like i did. One day it got so bad I had to confess. He said he was hurt but that we weren’t together. After we had the conversation and my mind immediately went to “oh you told him you slept with someone else but you didn’t tell him it was your ex” so now i’ve been ruminating over that. and that turned into ruminating over every single little detail of that night. I feel sick to my stomach, its been so debilitating I cant really do anything anymore because of it. We already had that conversation and I thought i would feel better but my mind found something else to obsess over. I’ve been thinking about bringing it up and telling him it was my ex but I have no idea if I should. But I know that if i dont, it will eat me alive. I just dont wanna hurt him. I really do love him and he’s so sweet. He’s the best thing that’s ever happened to me and the idea of losing him makes me sick to my stomach.