I CAN'T BELIEVE WHAT HE DID TO MY FAMILY AND DOG!!!

I absoluetly despise my step dad. My mom, grandma, husband, and I all went on vacation. He didn't want to, so he stayed behind with the family dog. My mom left him $50 for cigarettes, and we were only gonna be gone for 3 days. He is a chain smoker, so by day 2, he was out of cigarettes. I had to go to the hospital in another state for my asthma, so we were gone longer than expected, so then my stepdad calls and yells at us. He is screaming when are we coming back, and he is out of cigarettes and food (he makes his own money. He just likes to blow it, and then have my mom support him). He didn't believe I was in the hospital, so we even had him talk to a nurse, and he was so rude to her. She shook her head like she's not dealing with this. He then says he's divorcing my mom, and he reported her to adult protective services and lied saying she abused him. He took his name off the car. It's one of those cars that if it isn't paid they can shut it off anywhere at anytime, and we were on the freeway, and the payment was due that day, so me being the one with the most money, I had to pay it, so we wouldn't be stranded. We get home, and it turns out he locked our dog into the apartment without food for three days, and there was poop everywhere, and my step dad ransacked my grandma's apartment, and left all the lights on to run up her electricity bill. I was beyond done at this point. He never messes with me because me and him have actually physically fought before, and I won, so of course, he avoids me as much as he can. He's an abusive fuck. However, he treats everyone else like garbage, and my mom took his ass back after he apologized. THIS ALL STARTED OVER CIGARETTES!!! Update: My mom has always had a codependency issue. That's why she refuses to leave him. It's her fourth marriage, and she also doesn't want to get divorced again.