AITA?

My kiddos were fighting (pushing and laying on top of each other, mostly having fun but sometimes go too far). They are 5 and almost 3. They love each other to pieces. Anyways, they were playing on our bed and one got hurt. My husband yelled at them to stop. They did it again and he once again yelled at them to stop. Our 5 year old laid across the both of them (my husband and toddler) and my husband freaked out. He jolted him up by his arm, pushed him away towards the end of the bed and then kicked him in the arm/side. I yelled at him like what the actual fuck was that and why did you do that to our FIVE year old. He said that he needs to learn to listen and the only way to do that is to hurt him. He said the push didn't hurt him the kick did! I said YOU CANNOT KICK OUR KIDS AS "DISCIPLINE". He said yes he can and that he can do whatever he wants and if I don't like his parenting style then I can just get the fuck out. He said that I was out of line for calling out the way he parents in front of our children. I just I don't even know how I am the bad person here? Am I?