Would you say something to the bio mom?

I have 2 step kids. They're both 16. 10 months apart. My step daughter is ok. I don't see her much. She's more of a mamas girl. My step son I see every weekend although he's trying to come stay with us but my husband said no until he gets clean. He does drugs. My husband's heart breaks every time he sees his sons arm. It's covered in needle marks. My husband doesn't want that around our 8 years old. My step sons bio mom seems not to like him that much because she conceived him shortly after having hee daughter because she cheated on her husband with mine(before we were together) and ig blames him for the divorce. At least that's how she acts. We met her up at the grocery store so he could go with his mom but we still had to shop. My husband was talking to her about my step daughters grades when his mom grabbed him and pulled him to the side. Me and my husband went to see if everything was okay and she's yelling at him In a corner about texts between him and his friends. She said "Why are you still telling people this! Do you know you can get David in trouble!" David is her boyfriend. He wasn't saying anything "He NEVER touched you so stop telling your little friends this". My step son told her he did and she yelled at him to stop blaming David for why he does drugs. So my husband went over to her to ask what he's talking about so she grabs his son and goes into the middle of the store and yells "IM A HEARTBROKEN MOTHER WITH A SON WHO GETS IN TROUBLE AND BLAMES ME FOR HIM BEING HOOKED ON DRUGS!!!' He's covering his face at this point and she said "I GUESS NO MATTER WHAT I'M THE REASON FOR ALL YOUR MISTAKES!" Then she runs out with their daughter crying. Jesus Christ! My husband says nothing and just tells my step son he can come back to his house today and he will take him to school tomorrow. I just wish I said something whole she was humiliating him like that. My step daughter is with her mom but step son is here.