Look at what is working and stick to that-it looks like your W has noticed the changes your making and that has made her curious-think about what attracted her to you when you first met and work on them qualities-make any exchange you,s have now pleasant.
Act like you've accepted what she wants
Your there for your girls, they know that you are the solid parent for now but your doing the right thing by not getting mad at their mum in front of them-they need to know they can come to you in confidence
Their little world has been rocked so you be their rock
I think your right about your W new relationship-the honeymoon period is probably coming to a end but this will go on for a while yet
Patience is what you need now.
On bad days come here to vent journal and get angry.