Mighty,

Put yourself in XH's shoes:

-He divorced you
-He sees you as XW
-He has a new baby girl
-He cannot look like a d!ck for abandoning this woman with a newborn baby

I suspect that the last one is the real driving force for XH.

As a divorced man, XH is entitled to his choices.

Why do you keep expecting him to act differently?

Why do you chastise XH for "being arrogant" when he feels and acts like a divorced man?

Detach.

Take the reins of your own life. Live it up to the fullest.
You owe it to yourself and your kids this.

He is so whipped by this chick. He was last year and it was obvious, and even my son said so. And now, you can see it again. WTF!

Why do you even care? That is XH's cross to bear, not yours. Set him free. Wash your hands off of this problem.