You are right FM, abusive people do not change.
He has to first acknowledge truthfully to 'himself' that he is an abusive person. Secondly he would need to 'want' to change his abusive behaviour and thirdly he would need to seriously seek out the avenues to make change a possibility. And all..by..himself. Not because you or anyone else tells him so.
"He has told you oh so many times that he has changed." That is a very easy thing to spout. Has he always believed that just saying so means so? Case in point, that is how very far he has to come before he even has a shot of any meaningful change.
I bet if a professional asked him to list 10 examples of what his abusive behaviour entailed , he would be hard pressed. I'm not sure his definition of abusive behaviour is the same as the populace.
I hope this is the beginning of you finally being able to get on with your life and any communication between the two of you is short and to the point regarding your children. End of story.