This may be a few days late but MY opinion is I wouldn't write a letter or have ANY communications with them at all, it would be a closed book and the end of that story.

ANYONE who mistreats ANY animal WILL and DOES also mistreat humans, as he has already proven by not respecting your wishes in YOUR home or respecting your fur kid. I personally, prefer NOT to assosciate with people like that since he could put on the appearance of being sorry to get back in your good graces and then continue to mistreat her behind your back.

There seems to be to much negativetivity around your Mom and her choice of men and WHY would you subject yourself to that? I am the sort of person that if a person does not respect ME and mine, I do not want them around me, no matter WHO they are. As much as I loved my Mom, I was forced to tell her several times that if she was going to continue to act like she could get at times, I would NOT be coming around and did not want her at MY house. I just will not tolerate all that, life is to short to live that way. My step Dad I totally banned from my house and being around my children when they were small because of his drinking and fowel mouth... BUT, he knew I loved him and I was always there when he needed me and he knew what lines NOT to cross with me.

I am VERY strict with the people I love and am real quick to draw the lines they better not cross. The first time I would have caught someone being mean to one of my babies, I would have told them the very NEXT time they did that, WOULD be that LAST and the next time, they would no longer be welcome in my home anymore and I would not let them in.... But I know not everybody is like I am and you do what you feel you need to do. NO ONE mistreates MINE under ANY circumstances, no matter WHO it is! (I have dumped many boyfriends over my cats)