Prayer Request: Emotional Happenings

I realize that breakups are always hard and that I'm not unique, but I'm having a really hard time with this and thought I would share it here for prayer. I need some peace in this.

I've been seriously dating a girl for about 5 months now. A little over a month ago she went off to grad school in Saudi Arabia. Since we planned to make a future together, long distance seemed like the only sensible option.

3 weeks in she met a guy, stayed at his house to get to know him for 12 hours, slept with him, didn't leave his house for the next 48 hours, and has been dating him ever since. She broke up with me 2 days after the initial incident and gave me a bogus explanation, finally told me she cheated about 5 days after that, and finally told me the whole story just now (two weeks after the initial incident).

Needless to say, I am in a lot of shock and a lot of pain. This was a relationship that I pretty securely believed until we broke up was leading to a marriage, and to lose it and then be informed of what had been happening in my absence is absolutely surreal.