Hi Sam, My deepest apologies for the situation you're in. I've just been through the exact same thing this past 16 months.
I wanted to back what Eric said. Be very careful here. This is what my XH did to me...tried to be too nice in hopes to get what he wanted. I thought his being nice was a sign that he still cared, and I allowed him to cake eat a while too. Eric was right, as long as she gets what she wants she will play nice.
My advice I would've given myself 16 months ago when i was in your shoes : Make your choices very wisely, and make them according to how it will effect your life as a single person down the road.