Is this the last straw, or am I overreacting?

Sounds like your 2 year old is more mature than your husband. If you have to worry about him hurting your son, which it sounds like you do, you need to leave him. Even if he's not physically abusive emotional and verbal abuse effects kids just as badly and that would be a terrible way for your son to grow up. And throwing things at the cats is animal cruelty.