This is my first post here, so I apologize if I mess up any formatting.

To add context to this story, I’m a college student and have a fairly large friend group made up of couples and a lot of people that have slept with each other. This past weekend, I was planning on going to a date party with a girl I had been talking to, but she told me last minute that she couldn’t go. I didn’t really mind and instead planned on staying in that night instead. After she told me, I heard two of my friends (we’ll call them Sarah and Jess) walk into my apartment and went to say what’s up to them. They asked me who I was taking to the party and I explained that I wasn’t going because my date cancelled on me. Sarah suggested I take Jess as my date since Jess was planning on third wheeling with Sarah and her boyfriend. This is where it gets complicated.

Jess had dated one of my friends, Bob, for about a year and a half in the past, but they’ve been broken up for 3-4 months to my knowledge. I hesitated when Sarah asked me to take Jess because I knew she had history with Bob, but I ended up saying yes in a split second decision. Now, I had talked with Jess in the past about how things ended with Bob, and she said that they ended on good terms, and mutually agreed to end their relationship because they’d fallen out of love. I hadn’t talked to Bob about it because even though we’re friends, he’s not someone I’d say I’m super close with, so we never really talk about relationship problems.

Anyways, I end up going to the party pregame with Jess, and I bring a fifth of liquor for us to drink at the party, same as everyone. I got to the party and Jess tells me to start drinking because I need to catch up to her level. I start taking shots and feel pretty good, and she starts taking some with me. We get a little more than a third of the way through the bottle, and at this point I’m definitely feeling the liquor, but she keeps on encouraging me to drink with her and everyone else so I do. We end up finishing the bottle in about an hour and a half, and we’re both fucked up. We decide to head to a different pregame before the date party, and this is where my memory gets hazy.

I remember going to the next pregame for a few minutes, but the next thing I remember is waking up in bed in the middle of having sex with Jess. When this happened, she he last thing on my mind was dealing with the fallout of fucking my friends ex, so I finish the deed. We both end up falling asleep after we finish and next thing I know it’s the morning and I’m waking up next to her. I was still a little drunk in the morning, but I immediately start to realize what had happened the night before.

Jess gets picked up by her friend that morning and I go to my roommates room to talk about the night. I had my roommate and another good friend there and their first question was if I slept with Jess. I told them yes and they both start laughing because they couldn’t believe it. They both said that Jess is one of the last people they could see me sleeping with, and I agreed with them. To clarify, Jess has been a part of or friend group for a couple years now, and up until this weekend her and I had had a strictly platonic friendship. Although she’s an attractive girl, I’d never thought of sleeping with her for multiple reasons, primarily because she had dated Bob. I had absolutely no intentions of sleeping with her that night and my friends new that, but alcohol changes things.

After talking with my roommates I went to hang out with some other friends only to found out that they new what had happened between me and Jess. I only told my roommates, but so many other people found out. I definitely think Jess told her friends, who told other people, and so on. Jess is known to have a big mouth, so that just complicated things even further.

My main problem is that I fell like it will eventually get back to Bob since we have so many mutual friends, and I’m debating on whether or not to tell him myself. I feel like it’s the right thing to do because at the end of the day, I chose to take Jess and I’ve gotta be accountable for everything else that happened after. As much as I want to tell him myself, there’s a part of me hoping that he somehow never finds out. There’s another part saying that it’s not a big deal because they’ve been broken up for months and ended on good terms, but I know people don’t think like that when stuff involves their ex. Also, I don’t think I’d be cool with my friend sleeping with my ex.

Any advice would be helpful at this point because I want to do the best thing in this fucked up situation.

TL;DR: I slept with my friends ex girlfriend after I got black out drunk at a party, and I’m wondering if I should tell him myself or not.