The sea is so wide, and my boat is so small.
Your husband betrayed all of you. Your son's feelings of betrayal and anger are every bit as valid as everyone else's. If your husband hasn't made an effort to be remorseful and address it in a way that helps your son, he frankly had that comment coming.
That's one thing that just isn't negotiable: respect is earned. If you act like a jerk, people will respond to that. I think it was brave and healthy that your son was able to communicate his anger and sadness in a principled manner. He could have acted out, he could have been self-harming. Instead, he was direct (which apparently your husband still hasn't been brave enough to be with the sulking and not talking to you when you were distraught) and addressed the truth of what was going on.
Reality is hitting your husband? I HOPE SO.
No coddling the guy who stood silently and let you sob. No giving him credit for patriarchal street cred (Dad must be respected and obeyed, etc)that he didn't earn in that situation: he threw a tantrum, sulked, then didn't offer anything to address directly what he did.
This isn't un-fixable, but holy hell, don't blame the 13 yr old for communicating when the father chose not to.
I have a 13 yr son, too. Really hard age under ideal conditions. Your husband chose the situation; your son didn't.
My heart is broken for you thinking of you sobbing and him standing there silent. Hugs, Broken. I'm so sorry.