First, the only way a lien can be places on a home is if the deed holder is sued and becomes subject of a judgment. Are you on the deed?
Second, Sallie Mae can only sue if this is a private loan. Federal loans are only sued upon by the Dept. of Justice when the loan is assigned to them by the Dept. of Ed. That being said, is this a private loan? Check with a local consumer attorney as to what Sallie Mae can really do based on the type of loan this is.