changing jobs isn't running away from your demands when you had an affair with someone you worked with. At that point you ahve to weigh out your priorties, you can always find another job not to mention it would help take away your tendencies to think about her.
And when you say you need to face them and show her you can handle this and be mature, which "her" are you referring to? Your wife or the other woman? Becasue your focus as you know, should be on your wife if your chosing to work things out.
If you can't handle the thorns, don't crave the rose!!