There is OM in the picture whom W says she will absolutely give up IF I can commit to trying on the marriage again.
Your answer to her is..
"I have decided that I am not interested in reconciling. I have realized that it is not in the best interest of "us" as a couple and an even MORE important FACT is that I have lost trust. I will always love you because you are the mother of our child, but I am not IN love with you.(that one always gets to them) I realized that it just won't work for ME because I don't want to be with a woman I don't trust and am not in love with. Also add to the fact that you are STILL with him even now and are making it seem as if you are doing ME a favor by telling me you will leave him IF I commit to the relationship. I have decided that isn't going to happen. So, for now I want to proceed with the divorce."
Say this with confidence, resolve and matter of fact....
Don't BUDGE an inch if she doesn't dump him BEFORE you commit. Shame on you if you fall for that old trick.
"What is best for my kids is best for me"
Persevere = happily being patient over a long period of time