Can someone please shoot me now 😰

Okay so my Ex and I were hanging out which led to smoking pot and of course our favorite thing drinking vodka. All these things are a horrible combination I know. We agreed that we would be just friends since he had a girlfriend... and well I fucked up big time and he fingered me. Which in turn led me to beg and of course we had sex. I feel like a complete whore now and can't and won't talk to him now. I don't know weather to leave it bee or come clean to his girlfriend who is an amazing person. I don't know her well but I've only heard good things. I want to do the right thing since I made such a huge mistake. Please don't judge me I need to know though what I should do and hopefully I can salvage some self worth.