30 days after breakup already sleeping with another guy

[heartbroken1234]

Alright, so my girlfriend and I broke up a little over a month ago. The reason being that " she didn't feel as if I loved her enough.." She claimed to not feel assurance of my feelings... Because I wouldn't cuddle enough, go to the park, just little things like that. This was all very sudden and outta the blue. I had been staying with her for almost 6-7 months during the school year so I didn't have to commute. Then when the school year was over, I moved back home to get my job back. She took this very personal and claimed that I was using her as a convenience and place to stay. Which was not true at all, because I had friends place's to stay before I met her during the school year. I understand that she was hurt because we didn't see each other every single day and spend every second together, but she freaked. Not even a week into summer break, she claims she feels as if she doesn't even have a boyfriend. All the while, she's been talking more and more with her brother's best friend, who has always had a thing for her. I didn't think much of it, because she told me it was nothing and we both knew about the kid and how he's been with like 20 plus women and doesn't believe in God. So, 2 fairly big things when considering being serious w/ someone. Anyways... 2 weeks into summer break, we go on a cruise together with my family, and it went great!!! Not one argument, not one fight, notta thing, just perfect. After the cruise we were decent until like a week. Then she started saying I don't need to come up as much, which really frustrated me, because when I didn't visit her, she'd be around that kid. Anyways, we ended up arguing about it all the time, and she ended up breaking up with me. Then, the next 30 days after that were all arguing. Me accusing her of being with him and what not. Her telling me and my friends it's nothing, and even her brother. Until I find out by being a bad person and snooping through her messages where I found out they have been sleeping together. Of course I call her out on it, and she is just hysterical and humiliated. Up until a week before I found out though, she had been still saying I love you. Also, she'd always get mad at me for doing things with other girls, hanging out, accusing me of moving on, etc. All the while, she is having sex with this kid and staying with each other quite often. ( basically in a serious relationship). I don't know what to think of all this, I'm still tremendously in love with her and can't imagine losing her for good, I don't know what to do.