Can my ex (who I was not married to) sue me for mortgage, since I moved out and/or expenses incurred during the relationship?

Asked in Fort Lauderdale, FL - 11 months

My ex and I (who I was not married to) purchased a home together in Florida. Since he makes a good living and I am a full time student, I was the one that moved out. I told him that I would sign the house over to him as long as he refinanced to get my name off of the mortgage at the same time. I did not ask for reimbursement for my downpayment, renovations or any other items in the house. He said that the mortgage was too much for him (although he could afford it) and he decided to move forward with a loan modification with the Bank. I urged against doing this since, as indicated in multiple places on the internet, this process generally forces people into foreclosure. I then recommended that we attempt to do a short sale (since we are underwater) on the property, if he could not afford it. Since then, he reduced his payments, was denied the remodification and we are now in default of the mortgage. He is currently reapplying through a lawyer and I have been complying with the process. Several documents that I have signed state that the owners must live in the primary residence to be approved. Representatives from the bank have confirmed this. I clearly stated to my ex and his lawyer that I will not pretend that I live on the property. I continually cross out any lies about this but I am concerned that they are switching out pages and making it look as if I live there. Could I get in trouble for this? More importantly my ex is threatening to sue me for unpaid mortgage that has accrued since I moved out, as well as other expenses during our relationship. He is also refusing to sign over my car title to me. I paid for 100% of my car. We added him for a reduced insurance rate. Can he do that? By the way, I do not have any money or assets as I am a student. Any advice would be wonderful!