<human>: Hi reddit. 

My girlfriend and I recently broke up. We were dating for about 3 months or so. It's been about 4 days since the break up. 

First, my girlfriend lied to me. The night of 4th of July she told me she was going home after work. She later tells me she went out drinking that night with people from work. I was really upset she hid this from me because I don't like her out drinking without me because she gets very sloppy at times. 

So today at a friends, they ask why we broke up. I said I didn't want to talk about it and they say that they heard something really bad happened between us and that's why we broke up. I had no idea what he was talking about. Then he told me.

This was an actual party. At least 50 people. All our age. They went swimming in the pool and after a lot of them got in the shower; both guys and girls. All naked. She took off her top. She said she left on her bottoms. She said no one touched her and she didn't touch anyone, but I felt so sick to my stomach hearing this. She said she did it because she was unhappy with our relationship and because we were fighting all the time. 

We were fighting, but does this justify her actions? I'm so hurt inside right now to think that she cheated on me while we were still dating. She never told me. I had to find out from other people.

Give me a shortened version of the text
<bot>: Girlfriend took off top in shower with naked girls and guys. Said she did it because she was mad we were fighting all the time. Is it justifiable?