My landlord entered my condo without telling me, now threatening eviction, whats my recourse?

My landlord sent me an e-mail saying he will come to see my condo on Sunday afternoon, because he wants to sell it. He came that day, and indicated no problem. The next day, my girlfriend came home and found him in the condo again; two days after, he called me and threatened me with eviction claiming the condo was dirty. It appears to me that this claim was made based on what he say after entering without us knowing, what legal recourse do I have?