no no no send him nothing.....you have a contarct with the person who you worked with and took the money from.
He has to take legal action with her not you if he wants to be a PITA. You owe him no more info on this order than you owe him on any other order you task in your shop. He might be putting up the cash for the shirts but he is not drinking at your bar. What would you tell him if he demanded every other comparable invoice you ever issued to see if you charged them the same relative (no punn intended) price.
Your only exposure here is a testimony in court if he decides to sue the lady you did business with.
Disclaimer... I am not a lawyer just a retired negotiator formally with the Mothers And Fathers Italian Association.
mooseman