What can I do for my sister who is being emotionally abused (very, very controlled) by her husband?

My sister admits that she should have divorced her husband years ago while there was still some money but now that they are essentially broke, she has no place to go nor enough money to go. Her husband totally controls everything - she can't get her own mail, he does the grocery shopping, he controls the TV remote, etc. HE spends money on what he wants but she can't. This scenario goes on and one. Both are fine mentally - at least as far as I can tell. I've considered turning him in for elder abuse but worry that things might get worse. My BIL will "get even" with my sister when she tries to assert herself. She is 78 and he is 81. Any suggestions?