Sorry to hear it is not going so well, IF you don't really want a divorce. Let your H file. As long as you and you kids are protected. Like he does not clean out your bank account. Time is free.
You said "He makes a point of bringing her up, and talking about what they are both doing every time I see him. I try not to let it bother me, but it does. " It is good that you can show no reaction even though I know it must hurt. Maybe we need other to chime in on this But I think It would not be unreasonable to CALMLY Just mater of fact let him know that you would prefer not to hear about what he and the OW did. And leave it at that. Try not to show any emotion either anger or hurt. I think he is really being an A$$ hole to rub it in. Maybe he is testing you for a reaction. Maybe he is looking for acceptance. But I think it you are uncomfortable with it you should let him know. If you don't then it will validate was he is doing is OK.
Please Yoyo, Olive Theo what do you peeps think husband
And if I claim to be a wise man, well It surely means that I don't know