Thanks for using a real name, the symbols from before were a challenge. You're going to find a wealth of help, once you are free from your current agent. Your previous paperwork needs to be reviewed and everything should be resolved before you come back on the market.
If the buyer is going to sue, chances are they will claim an equitable interest in the property which may prevent you from completing your next transaction. Any agent that you move forward with will be well served by having your contracts and listing agreement cleared by an attorney before investing time, money and energy to sell a house where no sale may be possible for a while.
Once everything is cleared up and you do go back on the market, have a clear understanding of who represents who. I will sell my own listings, but only in the best interest of my seller and only if I represent the seller only. Dual agency is a farce and is next to impossible to do as you've found out. In your case, I suspect the agent represented themselves looking for a double pay day. Because they have so much to lose, please, please, please invest some time and money with an attorney. Your next agent may have one they can set you up with for a minimal fee and they may even defer payment until closing.
Assuming there is no active contract, that everything has expired and you've done everything to cooperate, and it would appear gone above the call of duty, no one should sue. That doesn't mean they won't. No human can guarantee the action of another. Let us know how things turn out.