Girlfriend broke up with me and talks to her other ex?

[Paul R]

My girlfriend of a year and nine months broke up with me. We have broken up three times. We broke up two months ago. At the time I was very sad cause we were supposed to go on vacation together and she was talking to her other ex again and everything but we got back together a week before i left for vacation durring winter break. We were so happy on vacation we went to sleep together and everything it was great but, when we got back from vacation we kept going out for two weeks but she always had work and everything and one night we had plans to go out and she said she couldnt do anything and I got frustrated and stupid and I yelled at her really bad. She broke up with me and I felt horrible about it. Now, it has been a little over a week and I notice she is talking to her other ex again. All she ever did was talk about how stupid he was so I dont get it. She says she just talks to him. I love her with all my life. What do I do? I asked her to go to prom as friends but she says she doesnt know.