I really think his family should be dealt with by him. You can always contact her after she knows. She may contact you.
Remember that blood is thicker than water and depending on her, the relationship can goes sideways.
She will be able to see the boys through him.
I understand that he thinks you are poisoning the boys. As long as you are not speaking negatively about him, don't worry what others think.
I think part of the WAS's script is to blame their kids hurt and anger on the LBS. They can't seem to see that their own actions may have created these feelings as the kids independently see what is happening.
Over time your ability to take the high road will be seen.
