Sorry to say but your ABF, is an insensitive jerk. You only have a couple of months invested in this relationship, and I know you are feeling hurt, But you do not need this type of turmoil in your life...
At the rate he is going, he is soon to develop some medical issues, and then what? You and his ex wife are going to share the burden of caring for him? Personally, I think they deserve each other. Birds of a feather flock together ............
As you posted, you already know the answer, and I agree, Dump him, let it go. Go forward, you have all the closure you need from this relationship, no need for any additional contact.......... All my best to you