I would not pay him one red cent. I would check with the agency in your state that covers licensed building professionals (the contractors, etc). He sounds like a scam artist who gets his business via intimidation and leaning on peoples "values". Sort of a way to force folks to pay whatever he bills them for.

Be aware that since there was not work order or written, signed estimate (key word "written"), in most states the work was done for free. You also may have needed an inspection and/or permit. Be also aware that payment usually makes it a legal contract so if you pay him you are "on the hook" for any more charges he may want to go after you for. Make sure (if you do decide to pay him) that you mark PAID IN FULL clearly on the check/bank draft and get him to sign a recpt for it that says the same. Listen to your friend the lawyer. I think it would be wise to pay her to draft him a nasty-gram informing him to cease harrassing you. IMHO that is where you should spend your money.