The best thing I can think of is to take the kids to something so amazing that she will feel left out. I need ideas.
Heres an idea, read over that and think about your motives. Is that really the man you want to be? Only doing amazing things with your kids in spite of your ex? I get your mad and likely just blowing off steam but don't even go down that road.
Shift your focus to you and the kids and stop getting angry over YOUR expectations over what she should be doing. Stop looking at this as a temporary separation, people don't buy new houses during a separation. Its just a stepping stone to divorce and while theres always hope things could turn around you need to accept the reality of the situation so you can move forward and grow right now.
And to clarify, that doesn't mean you go file out of spite first, or start a new relationship that you aren't ready for, or become an [censored] to her for no reason. Grow as an individual and become the man you want to be.
Accept what is, let go of what was, and have faith in what will be
