FWIW, I'd suggest you get her out of the house before XMAS. XMAS together is not going to make her wake up, if anything it will drive her further away. It will be horrible for you, not great for the kids. Remembering it every year will be horrible for all involved whether or not you reconcile. It will not be pleasant, or pretty, or sweet. It will suck. Just sayin...
Can you come up with a plan of how with that extra $400/month she can move out now and you'd be in the same place financially as if you waited until June?
Good job NOT going with the sarcastic humor (which is really not so fun for others.) Better response: "Great -- really looking forward to enhanced financial status. Smart idea!"
