Having been in the same boat, though mine was after 24 years of marriage, if you can find it in your heart to forgive, then its wonderful to be able to put it behind you. The fact that she told you as soon as you quit the gang, speaks volumes as to why she cheated...as the others wrote, you weren't there, she didn't feel safe, secure, or cared for, and she turned to someone else.
Kudos to you for seeking counseling. My wife and I did the same after she cheated and while we have ended up separating, it wasn't because of the cheating. That was a big blow to our marriage, but it was, as it turned out, the tip of the iceberg.
Take comfort in knowing you two are doing everything you can to reconnect, and it sounds like its been a tremendous success. Congratulations!
