When bad temptations are in our way, sometimes the only course of action is to avoid them. I'm sure your music is very important to you but obviously so is your family. As a talented musician I'm sure you could find another band to play with. What would do the most damage at this point, to both yourself and others ; quit the band or be unfaithful to your wife? Alimony, child support, custody battles and juggling the kids back and forth? If your scheduled weekend with your kids is the same as your band's big gig, then what? I think the answer's crystal clear here.

Now would be a good time to work on the relationship with your wife as this should be your first priority, no doubt. Music is fine, but you have to do what you have to if you value this relationship.

You should have thought about your wife when you entered this relationship. You are now paying for your mistake. Perhaps you are feeling some of the pain that your wife is going through... but I doubt it. Cheating men never get my sympathy. If you were in such a bad married relationship, you should have left and given your wife more respect than to cheat. Bad luck for you