Unlawful detainer by bank?

I am being sued by the bank. Two years ago (April 2009) I moved out of my home after my BK Chapter 7 believing the bank was to take posession soon. I left the home vacant for the bank. I found that the bank completed a trustee sale on the home in November 2010, the home did not sell and is now a REO. I also was served by an attorney representing the bank stating that I live at the property and they want me out. I have found out that there are people (squatters) living there. The lawsuit names me and I do not know how to handle this. Of course, I can not even go after the squatters because I do not own the home. Please advise, Thank You