<human>: Can you summarize the given text in a few sentences?

We've been going through a rough patch, we decided to take a break this morning, just a week to get our head on straight and finish with finals so we can focus on our issues. 

Right before she left i found a picture on her phone of her with her co-worker, its a selfie and hes biting her earring. She says it was nothing and that he did it while she was taking it. 

I can't help but feel very uncomfortable, she always says he has a girlfriend, but I don't know in what world that's appropriate when you're with someone, for her and for him.

I know if she had found a picture on my phone where some girl had my ear in her mouth or i had done that to another girl, i would be a dead man. She apologized after i told her uncomfortable i was with it and i forgave her to prevent a fight right before our break, but i'm still seething.

We had decided to take a break before i even saw it and now i can't help but feel furious. 

What do i do? What does it mean? How can i calm down? What the hell?
<bot>: this morning, saw a picture on my gf's phone of another guy biting her ear from a week ago; we had decided to go on break last night (mutual)