No!!!! :heart-break: Keep fighting, don't give up!!!
Let him smirk. Be nothing but nice to him. First of all, for the sake of the Grand Daughter. Second, your in a no win situation going up against a biological parent. Let it play out without doing battle with him. If he's 1/2 the loser you say, he will eff it up all by himself. He may just want to spite you and as soon as he realizes the responsibility he's taking his perspective may change.