Your girl cheats on you then dumps you. How do you rebound?

So I was dating this girl for about a year a half. I lost my job about six months into the relationship. Man has this year sucked. Anyway, she was cool and seemed to really love me. The job loss meant that I had to move to another city, that was less expensive and where most of my work contacts were. She stayed where she was and we did long distance. Distance is tough, but it was working for a while. It really did seem like she was all about me. She wanted to take the next step in our relationship, but I kept telling her we had to wait, because my finances and my future are so uncertain right now. Then one day, bam, she dumps me with an email. The email basically accuses me of dragging my feet and taking her for granted. I was upset, of course, but I don't expect people to just wait forever. Then, like an idiot, I have this "ah ha" moment and realize she was right and that I should have taken the next step with her anyway. I call her up and ask if I can drive out to her city (10 hours away) and she says yes. So I do it. I get there and basically grovel and beg to take her to take me back. Telling her she was right and that I will move for her. So we get back together. The next day I ask a question about this other person who now appears to be in her life and it doesn’t look right. I have never, ever questioned this girls‘ faithfulness before. She is the last person you would think capable. Her answer is shady, and so I asked another, and another, and another. Over the next seven hours she lied and lied, but then finally spilled it: she had been cheating on me with him for months. I was really pissed off, clearly. After a few days of highly emotional discussions, I tell her, okay, everyone is better than their crappiest mistake and I tell her I am willing to work it out. And she tells me no. She also tells me that she basically never wants to talk to me again because the things I said and did when I found out were "weird." FML -- I never felt so dumb before.