Unfortunately, time wasted has played heavily into king Henry's hands. He prevails the more, because his combined military strength exceeds yours, and you have given him all the time he required to bring it to bear: you have no choice but to surrender on terms. At best, you will retain your duchy only under severe restrictions upon your future actions.
Because you are perceived by all the churchmen chroniclers as an enemy, you go down in history as William the (wicked) Bastard.