Amy's kids grew up in that house, there is no reason for her to leave. And a lot for her to stay. And the way Matt is trying to weasel it away from her is pretty tacky and low class.
If it were me Carens butt would have been fired a long time ago. The divorce was only a couple of years ago and it has become increasingly clear that Caren is a homewrecker. Having to smile and make nice cannot be easy even though Amy is far better off without Miserable Matt.