Hi - thanks for your post!
The good news is that you should not be liable for the foreclosure - - you were just the purchaser as the sale, so there should be no liability on you regarding the foreclosure. The worst case scenario for you would be if the foreclosure was found to be illegal, the transaction would be reversed and you should be entitled to your money back.
If suit is filed, you should discuss with your attorney the possibility of filing a counter-claim against the mortgage
company to repay you all of your costs and fees IF the court finds the foreclosure was improper/illegal.
In order for a court to enter a temporary restraining order, the judge usually requires a bond to be posted for 125% of the amount at issue so if the claim is not legitimate, the party has liability to the other parties. If the court requires a bond, it may stop him from filing this.
IF the court grants the TRO, it may stay in effect until the court determines the case. But, the court will require adequate proof before allowing the TRO. If this happens, all you can do is object and claim that the TRO is just a stalling tactic, that if the TRO is granted, that a bond be obtained by the former owner and that in the even there is a finding of an improper foreclosure, then you should be reimbursed by the lender