<human>: Can you condense the text into three sentences or less?

I'm a 22 year old male, she's an almost 21 year old female. We've been together almost two years. This last week I went to visit my family in Texas. While I was gone she slept with a random band member at a local bar performance. I found marks on her chest and she admitted it. She says it was a one time thing, but I'm not sure I can believe that given the circumstances. I am not sure if I should continue the relationship or not. We have generally had a good relationship, but the last few weeks she expressed concern that I wasn't paying her enough attention. Though, I am very busy with work and school and I tried to tell her that while she is/was the most important thing in my life, that my life cannot revolve around her. She is generally very narcissistic, but she is an actress so it is not to be surprising. We live together and have a lease. I have no friends I can go stay with. Can anyone tell me what they would do in my position?
<bot>: live-in girlfriend of 2 years gave some guy the business while I was on vacation and admitted it after I saw the evidence.