My father is behaving like this

My father is actually Chinese too so it's not about racism, at least. I believe it's partly his unstable mind and all the fights with my mother about the grandparents didn't help.
I believe my mother is far from innocent as well. She used physical force to make him oblige to letting her parents live with us.
But this occurred years ago. My mother has since gotten therapy and a lot of help and she has improved herself astoundingly. Meanwhile, my father feels attacked by my grandparents coming back even though he doesn't live under the same roof as them anymore and they want nothing to do with him...and he reacts in extreme ways