My first wife not only cheated on me, but she did it with my DRUMMER. The little skank broke up a marriage and a rhythm section at the SAME TIME. (I actually miss the drummer.) JLY and Edward G. hit it on the head. Find peace and be happy. She is about to be on a roller coaster. (They always end up screwing up more than once.) Her life will be rough for quite a while. Don't go on the same ride. Work out. Lose some weight (unless you are already healthy). Play more gigs. Be happy. It drives them NUTS when you do that. Two of my exes (one wife, one long-term girlfriend) still contact me every now and then. They try to bring misery into my life (which is impossible) because they can't STAND the fact that I was able to move on from them rather than crawl into some hole and shrivel up and die without them.
Drive her nuts! Go be happy! (After you lick your wounds for a little while, of course.)
Best of luck. Hang in there brother! There is life after the whore! I promise! I'm living proof!