You contact the IRS and send them the court order.

It is unclear who you think can or cannot sue who. But generally speaking anyone can sue, and a court will determine who wins. In other words,...

It is your lawyer's job to cross examine him on the alleged lies. That's how a trial works.

No you can't. You have no damages to sue for.

A lawyer would have to review the entire case file to give an opinion.

It is always hard to opine when we don't have all the facts, but nothing here sounds improper or illegal.

These scammers are usually located in another country, making suing them impossible.

Yes. There was no agreement...............................

This is not a legal issue. It is life. Deal with it.

The real issue is the bank won't release you. So you may need to sue the ex for any money you have to pay out.