<human>: Hey relationship_advice, this is a throwaway as I'd rather not post on my original account. 

Me and my girlfriend have known each other for quite some time. We had a little fling my Freshman year but things got serious Sophomore summer - Junior year of high school. I love who she is, how we act together,  everything is great and truly no one has made me happier of a person than her. And that's an understatement.  With that has come one complication, I've talked to other girls and she disapproves, I've changed and no longer do that. At the same time she was doing the same thing. Very flirtatious with other guys and we've fought multiple times over this same exact thing but nothing seems to change between her. She gave me her iPod to put music on and upon one suspicion I read one of her messages through Facebook including a guy where the flirting was mutual. The dialogue was about getting drunk, and she used the word 'baby', and having fun together. I'm moving over 100 miles to attend school where she will still remain in my hometown. After her senior year she is moving over 600 miles away. I really wanted to make this last, I've seen us together forever and the feeling is mutual between her as well. We planned on sacrificing a lot to make this work but lately I'm not sure if it will be worth it. 

I called her earlier after she got out of school explaining what I found in her messages, planning on ending it right there. She teared up very quickly and promised she has never cheated on me and I honestly believe that. Unknowingly she had a death in the family today and I felt horrible to make her cry more.

My heart is beating out of my chest and my thoughts are a million mile per hour.  I guess from you guys I would like some insight on how I should carry this out. We are talking later tonight and I have no clue what I should do.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Girlfriend of 1-2 years flirts with other guys. We are soon have an impending long distance relationship. Should I stay with her or end it.