My step son and his mom have a very toxic relationship

I've posted about my step son and his mom before but he went back home with his mom not too long ago and low and behold he his mom sends my son a video of my 15 year old step son losing it and there's damage all around the house. She is saying "I can't do this anymore. Your son is fucking psychotic". And he's yelling "Why do you always bring out your fucking camera after you pushed me to my breaking point. You're a manipulative fucking cunt'. And she was yelling at him staying look what he did to the house and he yelled "You did half of this! Stop acting like you don't put holes in walls or throw shit at me ". She said she didn't throw anything at him and he said she did and she is saying in the vide "Your son needs to go impatient. He can't stay here". And my step son yelled "I need to go. You're a bipolar manipulative bitch!" My husband called asking wtf they're fighting about this time and there was so much yelling and she yelled to come get his son so he's back here again. My husband is really bad at talking to his son and being the bad guy. But when they got home he was saying he should not be calling his mother or any women out her name and he was saying "So she can hit me and throw shit at me and tell me I should be grateful she didn't kill me because she thought about it when I was a baby". And he says she pushes and pushes and she puts holes in walls too but never records herself doing it and only records him when he blows up and that him mom has handed him a razer and told him "I'm done. Do what you want. Whatever happens, happens". Idk who's lying, I just know their relationship is so toxic. He said his mom wants people to think he's crazy to hide how abusive she is. She usually asks for him to come back in a few weeks after fights like this but my husband is saying regardless of who's telling the truth he thinks he should just get custody because their relationship is too toxic. Idk what do you guys think?

Edit: I've known him since he was 8 and I've never had issues besides normal teen attitude. He has put a hole in my wall a year ago but it was because my brother was being a creep and he snapped and I don't allow my brother around me anymore because he's a fucking creep. But besides that I've never had issues with him just destroying shit and cussing.