My former roommate, who was released with a roommate release form left some of her belongings in my apartment so I told her when she came to give me the keys and get her belongings that she will get them back as soon as I receive the rent and electric money she owes me. We are both on the lease and I had to pay for her last month of rent as well as our electric bill, which she said she would pay. She is now threatening to have a peace officer escort her to my apartment to get her belongings. Do I have the right to hold these items as collateral since she said she would pay the money she owes me? How do I get her to pay the rent? She raked up late fees and made me pay over a thousand dollars after she left.