If you want to "fight this" ... get a lawyer.
If you want to know whether "this is legal".... get a lawyer.
If you want help with CS ... get a lawyer.
If you want to just gripe to a bunch of strangers... post here.
Seriously, the correct way... the only correct way... to address your problems is to hire a lawyer.
My advice, find a family lawyer and then pay them for an hour of their time. Around here this costs $100-$120 for an initial consultation. You should make sure you are organized, before you go make sure you know all the information about your own finances and everything you know about his.
The lawyer will tell you whether you have a case, and give you real suggestions on how to proceed.
I would pay for an hour. This is a fairly common thing that lawyers do. You can often get a free initial consultation... but you get what you pay for (a free initial consultation will be a sales pitch with very little useful information).