Call your rental property insurance company

and make a claim about the case.  Normally they will ask you to go to their office, a claim adjuster will ask you details about what happened, you will give the adjustoer the copy of the lawyer's email, mold report and etc.  The insurance company will deal with the lawyer/tenant directly and this is why you need the property insurance.  I don't see you need to have any worries, I see much worse case than this.  The lawyer/tenant would get nothing in my opinion.  Ask your adjuster about how you should respond to the lawyer/tenant's request/email, most likely the adjuster will advise you "leave it to them" - means that you just forward his request/email to the adjuster.