I have a fair few relatives who had a lot of childhood behaviors that edged...really concerning stuff. Like hurting animals, setting fires, thinking that causing pain was hilarious, ugly "practical jokes" that are too fucked up to write about online, etc. I wouldn't worry about your son being like that cause he'd probably already be playing with animals in a very specific way or drawing torture scenes with his crayons tbh. (Lot of this behavior comes from childhood abuse and severe trauma.) It's pretty obvious to spot if the entire family isn't in flaming denial.

The bit that I picked up via observation, though, is that no one will afford you respect if you don't force them to respect you. People who only understand aggression do not hear polite no's and go "wow, this person is communicating, I should listen to them because I respect them." You've gotta make them. It doesn't matter why they're acting that way (depression, autism, whatever), you know? People get all up in their feelings about the whys and intentions and how XYZ isn't someone's fault, but emotions and reasons are a dime a dozen. Bluntly, who cares about the why if you don't like it?

Based off of what you've written, I very much imagine your son's behavior comes from modeling how other people treat you. The fact that multiple family members were in the house and disrespecting you--especially in front of your children--is unacceptable. I don't care who they are or what their problems are, you cannot let that happen. Yeah, it's not right, as the victim you shouldn't have to be the one to change your behavior, but still. You cannot model that behavior in front of your children.