Can I transfer title for part of my property that is being used as collateral to a loan?

I have 20 acre of land and all of it was used as collateral to build my home to which I got an FHA 30 year fix rate loan. When I divorced, my exhusband's attorney insisted that I decree over 18 acres of the land back to my ex. I signed the decree because it was his land in the first place, but I don't think I was legally able to Quit Claim it to anyone due to the collateralized loan on it. His attorney said it could be done and because I didn't want the land anyway, I signed the quit claim to let him know I was not intending to keep it. But I felt that legally I didn't own this property so how can I give it to anyone?  Am I right?  Did I not have the right to Quit claim this property until the loan is satisfied?