I don’t think this is a big deal at all. I don’t even think you’ve done anything wrong.

They basically gave you a hug you didn’t do anything wrong by being friendly. If you’re worried about it just delete the picture and press onward.

So what did you do wrong again?

the act is trivial, hiding such a trivial thing is overly escalating it, and that's what will be a red flag

next time this is relevant when you talk, bring it up, be honest, and then forget about it, but there shouldn't be any need to bottle up these feelings over such a small thing

You are overreacting, if you really feel like you have to tell your gf, odds are she really doesn't care

Have you and your girlfriend ever established such boundaries? For most people, hugging someone else than your partner is okay, for some it's not okay tho. If you ever talked about it and said its not okay, you should tell her and excuse, be honest and talk about it. It shouldn't be a big deal. If you never talked about it, then it's probably time to do so, she'll probably think it's fine

You feel guilty because those two girls thought you and your friend were single. I'll bet they even hit on you and it made you feel good. If they were your friends before that night, it wouldnt be anything, but they were strangers. Don't take advice from reddit incels who cant even get a girlfriend in the first place. Also, dont try to use the 'i was drunk' excuse- you knew what you were doing at the time (and if you didnt, you need to drink less around strangers). If you don't tell her about it, I bet the picture will appear again in the future. And when that happens, she'll know you were lying about something, and she'll think it's cheating.

Unless your erect dick is visible in the picture, or you’re doing a reach around to grab some side boob, you have little to worry about. People pose like this with friends and strangers all the time