WTBH, your situation is so different than mine. I have no experience to offer but I will send strength and hope.
The only advice I can give you is to ask is there any sort of domestic violence group or woman's advocacy group where you can get some free or cheap help with this issue? This isn't necessarily a al-anon or divorce issue but a legal one. Any allies/support you can pick up would be good.
BTW, I like the nanny cam idea as well.
Your friend,