am i responsible if i only signed the mortgage document on a line of credit and the person who took out the loan defautes

You need to review all of the documents very carefully to see what obligations you signed or committed to. If you only signed the mortgage, then only your interest in the subject property is subject to the lien of the mortgage. No other assets of yours should be available to the lender, nor should you be obligated under the promissory note or promise to pay that was given to the lender.  Again, you must check carefully all documents to determine what obligations you actually have, as sometimes line of credit documentation has combined the promise to pay with the mortgage document.  Before assuming anything you should have a good real estate attorney review your documents. This is specific to Florida law and does not constitute legal advice as the facts presented are anonymous and incomplete. This is intended for general education only and does not create an attorney-client relationship. This should not be relied on and you must seek your own attorney client relationship.