Unfortunately, there is nothing you can do to stop them from filing suit against you if they are set on doing so. Just be sure to have your proof ready and I would strongly recommend consulting with an attorney ahead of time. You have certain rights under state law and hopefully some language in your lease that protects you if the Landlord files suit and you win. They should not be able to change the trems of the lease and impose more than what the lease provides just because they were getting foreclosed on. An attorney can review all of your facts, your lease and help guide you forward.
LEGAL DISCLAIMER-An attorney can only give you competent legal advice if he or she knows all the facts and is licensed to practice law in the state specific to your question. The comments above are not intended to be legal advice but general comments based on the limited information provided in the question. I am only licensed to practice in the State of Tennessee.