Best friend lost it on my son, what do I do?

This is long, but I need advice.

Let me start by saying that my husband and I are not very strict parents. While we do discipline our kids, ground them for their grades, give them chores around the house, etc I don’t want them having a panic attack if they forget to say how high when we say jump, ya know? They are both good kids, they don’t get in trouble at school, my son is in advanced classes. My friend on the other hand is the complete opposite. They are very “I will say something once and if you don’t immediately obey shit will hit the fan” kind of parents. Husband was in the army and that’s how they run their house. Nothing wrong with it, we’re just very different.

Anyway, we were at their house last night and were standing outside talking. My 15 year old son does this thing when he’s trying to be funny and says the same thing over and over. Like you try to reply to him and he will just keep saying the same thing. It’s annoying, but whatever, no big deal right? Wrong.

So he’s doing that and I say something like “don’t you have people your own age to hang out with, go in the house” in a joking way. He keeps on, and my friend loses her shit! I don’t remember everything she said because we all thought she was joking at first, and honestly I was just completely surprised and trying to figure out what the hell was going on. What I do remember is “if you were husbands kid he would beat your ass!” My son asks why and she says a bunch of stuff and then ends with “your mom told you to go in the house multiple times! You’re a complete asshole and the sad thing is you’re too f***ing DUMB to realize it” emphasizing the “dumb”

What. The. Hell?! I’m not leaving anything out, he wasn’t saying anything mean or offensive. She brought up how everyone was posting stuff about 4/20 on facebook and her neighbor didn’t know what it was or something like that. He said something to the effect of “I don’t know what it is, what is it?” She says “you do too” and he just keeps going on about “nope, don’t know what that is, never heard of it” and giggling or something stupid like that. Again, when I told him to go inside I said it in a joking way, but even if I hadn’t it’s none of her business! He is MY child, and if he needs disciplined that is MY job! Now I will say that she has never seen me get onto my kids, if necessary we will talk to them when we leave, ground them if needed then, etc. My dad loved to yell and cuss me out in front of friends, which was humiliating, so I have a thing about punishing children in front of people.

I was so shocked that I didn’t say anything, just stood there like an idiot instead of taking up for my child. He says “wow” a couple of times and goes in. My husband changes the subject trying to smooth things over, I go to the bathroom to calm down because WTF?! I go back out and tell her that I need to get home and do laundry so we leave.

On the way home she texts me and apologizes “for cussing and calling him dumb.” Not all of it was out of line apparently, just that part. I’m livid, my son is trying to hide tears but I can see him wiping them away. He apologizes and tells me that if he knew I was being serious when I told him to go inside he would have (I wasn’t)

When we get home I go apologize for not taking up for him in the moment, and for the fact that it even happened at all. His eyes are bloodshot, he’s visibly upset, and asks me “when i’m joking around am I really just annoying?” I’m absolutely crushed. He has been very down on himself lately, to the point of us discussing finding him a therapist, and then this grown ass adult just stood there and tore him down.

She has been texting me this morning acting like nothing happened. I just haven’t replied because honestly I don’t even know what to say or do. I can’t just gloss over it and move on. Not to sound dramatic, but I feel like how we handle this is one of those things that can make or break our relationship with our son. My husband thinks I should tell her how I feel and have her apologize to him and then move on, but I almost feel like I would be betraying him by continuing our friendship at this point. Can I please get some outside opinions on this? Am I wrong for being so upset? How should I handle it going forward?