If one of my insiders were harming animals like that i would ask to be locked up - to be sent somewhere where that alter and i could get help, at the very least. I would plead for that even if my alter didn't want that. There is animal abuse in my hx too -things i won't get into

I have 4 cats and love them dearly. I know some of my insiders have the attitude that 'they're just cats' but, thankfully no one tries to harm them. The littles love them very much.

I would talk to the bf. Seems he wouldn't want this and would willing and wanting to do anything to stop it, even if it means being committed for awhile while he works with this insider to stop it and get it worked out. Just my opinion.
good luck