libel email defamation

My husband had a signed contract for a job in Florida last year. Many
others were hired for other positions for the same job, but did not have
signed contracts. The company \"fired\" everyone by email and never paid
anybody. An email was circulated to try to get the people involved to file
a class action lawsuit against the company. Many people were upset and
stated this in the emails they sent back and forth. My husband did not get
involved apart from telling the others via email that he had a signed
contract. He received a certified letter stating that the company is
planning to file a class action law suit. The letter states that due to the
\'light\' nature of my husband\'s participation, the company would like to
close this matter with my husband by terminating his contract with no
further obligation or owing and to bind him with a formal cease and desist
of all allegations made towards the company and the ending of all
relationships and communications with the successors and any other sources
associated with the company. The letter states that if my husband does not
acknowledge the letter the company will serve him with papers to appear in a
Florida court for damages not limited to $100,000 plus court and attorney
costs. We do not know where to start.

What would they be suing him for?

He does not seem to have done anything wrong?

He should not waive his rights if he did nothing wrong.