Help doing what is best for The Children

[Awoken]

It sounds like you handled this well. You listened and validated. Did you address the language S9 used?

Also said mom is trying to take them away from me again.

This is what concerns me. What is your take on what he said?

My kids are older than yours (D17, S13), and I have little certainty. Still, here are my thoughts:

I would reassure him about the risk to your relationship, let him know that you are on top of that situation. It's unfortunate, and he shouldn't be in the position of protecting you. He's basically "telling" on his mom. He will feel guilt over this kind of thing, even if it's the right thing to do.

My D17 started spying on my W. Since W trusted her, D17 had access to her computer. D17 discovered evidence of an EA, and a secret gmail account on her own. When she came to me with the information, told me she had seen bad "pictures", I could see the guilt all over face. I told her she didn't need to spy on mom, and I would take care of the situation. That it was important to me that she have a good relationship with her mom.

So far, it seems like the right choice, and I'm glad she's not carrying that burden now. I was very unsure of my decision! Still am. There is no real way to prepare for some of this.

There is another possibility. S9 could be lashing out at mom by telling you this information, and who knows how accurate it really is.