My girlfriend (F25) received a d*ckpic from a friend and she's underestimating the matter. I (M29) asked her to cut every contact with this guy.

I (M29) am having an argument with my girlfriend (F25) because she received a naked selfie in front of a mirror from her fresh friend she's playing squash with.

A little bit of contest:

When I met my girlfriend she recently broke up with her ex boyfriend and from her description the story with him was extremely toxic. I met the guy a couple of times and I can assure that he's a despicable pathetic person, who wanted to control her in every single moment of her day. He was denying her friendships because he did not liked the people she was hanging out, he induced her to take part to a threesome with another guy when she did not really wanted it. He's nonstop texting her to begging her to go back together, he vented the possibility of killing himself if she didn't agree to go back with him, and so on. Because of this, she all the time had a very poor social life.

She recently made friendship with a group of people (4F 2M) we met at a bar when we were together. They're ok guys, well mannered, funny and so on. One of the two M is really funny and my gf goes along with him, they started playing squash together recently and they started hanging out with the whole group, even without me. I am ok with this: there's no happy relationship if there's no trust.

I started smelling something (not that they did something or that she cheated on me) when this guy started making some weird jokes, she was showing me her DMs with him without me asking thinking it was funny, about some "double cardio" after the squash session, when he started appearing out of nowhere when she was outside with him, or inviting her out for dinner or lunch (she never accepted). One evening this guy reached his group of friends, when my gf was with them, and she told me that he sniffed multiple times her jacket after he proposed her to hold the jacket for her... I was telling her that this guy was not ok and he was lowkey hitting on her or sensing the waters.

The other evening, we were going to sleep, she received a message from him, it was a picture, she told me "oh look, M. sent me a picture", we opened it and it was a naked selfie in the dark in front of a mirror... I was speechless: because of the picture but mostly because of the fact that she was not and she is still not considering this fact as something non-acceptable.

After some thinking, I told her that he trespassed the line and she has to cut every contact with him, I cannot stand her going to squash or other events with this person. She's upset because she's seeing herself again being neglected a friendship from his boyfriend (before with her ex and now with me) but this for me is out of mind: I'd be more than happy if she could find some good friend; I explained to her my reasons why this guy doesn't want to be her friend, or at least only a friend (wasn't it clear???). I truly believe that she was looking only for a friendship relationship with this guy but he overstepped the "line" and I am having doubts about myself being strict on the "cut every contact".

As per I do not want her to stay with me because I love her, but because she should love me and want me, I know that I cannot force decisions on her.

She told me that she will talk with this guy and tell him that this is completely out of place and does not have to happen anymore... But to me this is not enough, I cannot stand the idea of her meeting, on a friendly way, with this guy again, after what happened.