Do not hold things lady hostage to your emotions. Sounds like she needs to block you. These are words that should have been said before you left.

I would send that text message to her from your phone while she's sitting next yo you and tell her to start talking. Then, after she tells her washed down version. I would call the friend and tell her that gf told you everything and you want to confirm with her exactly who was with man 1 and 2. Hopefully, you get their names.

Then, if the relationship is over, you make an exit plan. It is workable you find a therapist to help navigate the road to trusting again

Seems odd he just decided to do this 1 time. I'd worry about the other sent out nudes you know nothing about. I'm sorry you're dealing with this. There's a saying. For every rat you see, there are many more hiding in the woodwork.

Your bf cheated. He went on a double date with his friend. You deserve better. I would get in Touch with the friends ex and find out how often your bf was with this friend when he was out cheating. There's more to the story here.

You need to get in touch with her parents.