Sorry to hear your troubles. Makes me wonder how fast the tow-boat was going?
Note to self, when being towed tie off to the mast.
ONLY if the mast is keel-stepped! If the boat has a deck-stepped mast the mast step could be ripped off the deck (or if the towline slipped up the mast a bit..... bye-bye mast).
Another good (and with a deck-stepped mast, much better) attachment point for towing a sailboat would be a bridle from the two jibsheet winches forward along the deck and use the bow cleats as "chocks". Could also use this idea to tow off the stern if you lead the bridle aft.
For a vessel HARD aground, the best idea is usually to wrap a line or strap completely around the boat's hull and tied off by short lines to hold it in place along the sides. That puts much less strain on hardware, since the force is all on the hull.
Might have been better for this boat to have just waited for high tide ,unless exposed to waves.