The decision is never an easy one, and although my situation has been contracted immensely by W's desire to play scorched-earth and attempt to alienate my D1, I still find it hard not to feel sympathy for someone who obviously has a host of problems, and which we are the last person they want to seek for help.
Loving detachment is hard, but ultimately it is loving because we allow our loved ones to make the mistakes they need to make in order to grow as a person and learn from. Busting up your W's A was the right thing to do, but I'm sure she still held a deep-seated resentment that you were able to one-up her (Narcissists can't help it) and that is something that was going to be difficult to get past because she probably finds it difficult to admit wrongdoing.
Ultimately we deserve better, whether from our spouse or someone else. It is impossible to have a healthy emotional balance in a one-way relationship. We can only carry the load so long ourselves, and I think the decision you are making is one many couples are making during this rough economic period.
I wish you the best, and hope you continue checking in with us and giving us advice.
"You can't reason someone out of a position they didn't reason themselves into."