Quoting TTCbbno5:" I've tried to say nothing... she know it's wrong. I try to just listen. I can't believe she bought a ... [snip!] ... tell her what she is worth and that he is far below what she deserves. I think she's more staying for the kids than anything."
That , IMO, is the worst thing you can do.
If you are unhappy and treated badly, your kids will see it and grow up thinking this behavior is okay.
I would offer her as much support and help as she is willing to take, but if she doesn't want the help , its going to suck, but not much you can do.