Does my ex-roommate have a legal leg to stand on?

She owned the house. I lived there over a yr. w/o a formal agreement - we used to be friends. We had a falling out and I found a new place to live, which caused her to flip out (girl is crazy). She kicked me out the day she discovered I was moving (3 wks early)- called the police to have me removed, etc. I moved out and paid rent & util's for the entire time I was there, as well as $300 extra for 'damages' she claimed my cats made. When I went to pick up my stuff the last time, she forced me to sign something saying I would go back and make repairs on the damages (b/c she wanted an add'l $200 that I didn't have). She would not let me leave w/o signing. It was witnessed by her mom and my friend. She was holding my items hostage and refused to let me get them w/o signing. I know - I should have called the cops b/c tenants have rights, but I didn't want to take it that far. In retrospect, I never woud have signed. Does the fact that she was threatening me void the contract?