My Ex-roommate is stating that I still owe her for utility bills that were in her name. She recently moved out, and spent her last 2 months in the apartment rent-free (I covered her share). I also put out $ for all other expenses in the household - any necessities and food shopping. She is asking me to send HER a check for $700 so she can pay the utility bills. If she decides to take this matter to court - how strong is her case?