My paternal grandma died last year. And my dad remarried in 2017.

Not really enough time for his new wife to establish much rapport.

Das had always been a Mama’s boy and lived most all of his life clinging to his mom’s skirts anyway.

Yet when grandma died it was the new wife who casually sent me a picture taken with her phone of my grandma’s corpse in the hospital bed.

Horrifying, and very inappropriate. All of this is to say that I can relate to your situation and no, you aren’t overreacting.