Need to blow off some steam, somebody give advice?

Buddy, flirting never has been nor will it ever be cheating. That you don't have to worry about. Everybody flirts, even you. The fact that she's texting this guy every night before bed and instead of you should have you worried however. That will lead to some problems in the near future, promise you that. But the answer to your question is, take a guess now. Talk to her. Of course she doesn't know how these things make you feel because I guarantee you that you haven't even brought up this topic of conversation to her as of yet. Talk to her and find out what she really wants in the relationship. If you don't want her talking to his guy tell her, and tell her why. If she really loves you and wants to be with you she will stop talking to him instantaneously. As for the folks that may say that you shouldn't ask her to do that. Yes you should. If it bothers you she should have no problem with stopping it.