Husband's ex is putting kids in the middle?

Two sweet kids, 13 & 11. My husband's ex-wife and her new husband speak ill of myself and my husband in front of the kids. They yell out obscenities to us in front of the kids, make fun of us in front of the kids. The mother tells her kids in a joking way about how her new husband wants to kick their dad's a#@ (seriously? are we in high school??). She confides in them as of they are her friends, rather than her children and it is causing so many problems with them. Our daughter was hospitalized for a week with stomach pains, she wouldn't eat, etc. After many tests, the doctors ruled it anorexia. This...after her whole family came outside during a pick up at Thanksgiving and called myself and my husband fat; stating that we had double chins and they wanted to count the chins in the front seat. In FRONT OF THE KIDS! Now she is obsessed with washing her hands and germs...Our son is overweight quite a bit, but he is a wonderful boy and we have him in sports, etc. to help his weight issues. He isn't sensitive about his weight and we don't bring it to the forefront of our everyday, but their mother does. Now she and her husband are amping up the trash talk of my husband. We are very non-confrontational people, we try to take the high road and not engage in the crap, but now it's hurting our kids. When they come over (we have 50/50 custody and do the week to week schedule), they show my husband and I no respect, they act like they don't want to be here and when their mother calls them(which is 3-4 times a day), they spring up and go into their rooms and talk to her with the doors shut. She grills them for information and so we have to guard what we let the kids know, because no matter what, they take the information back to her. They fear her being mad at them to the point that they would rather hurt their father than not abide by their mother's wishes. It's killing my husband, he loves those kids so very much and has always done anything and everything for them! We fear now that she is talking them into speaking with a judge about living with her full-time. When they are here, it takes a few hours for them to adjust back to being home, but once they are home, we have a great time! We play games, we do family activities, we try to keep a very stable environment for them. But, her wrath (and let me tell you, this woman is HORRIBLE!!!) scares them and they will do anything and everything to keep her happy...at anyone's expense.