You are a person with emotions. You reacted to something that happened to you. You are not perfect só your reaction maybe wasnt the best. Its ok.

You cant just go from having a romantic relation with a person, to seeing them date with other people the next day. Hell, it can even hurt years after. We dont control what we feel, all we do is learn how to deal with them. You're are still young.

IMO this is not a FU.

You will be alright.

Also, that guy wanted you to know he was dating. Trust me.

Ok...

She said it was ok for you to touch her breasts? Was there some interaction before that, that lead to that?

Was she trying to normalize the situation as a coping mechanism?

Idk dude, If you started touching her without any form of previous consent, she shouldnt trust you ever again. Being drunk is not a justification.

If... And this is a big IF... you started making out and she was not ready for that kind of touching and she made it clear, that would be just two people getting frisky and finding each others bounderies.

I think you should write to her letting her know what you think happened. What ever she decides to do, you got to live with that.

If it really went as you said and you just started groping her from nothing, you need to work out your shit, man. If you cant trust yourself, drunk or not, you shouldnt be around that girl or any until you learn to control yourself.

Edit: i forgot to say, its a good thing you Stoped when she asked. Dont feel suicidal, take this as a formative experience.

PLEASE look for help If you cant control your depression.