Eric, I learned that the best approach with In laws and H's friends is to stay out of it as much as possible. No calls, no emails, nothing. When I do interact with them I am pleasant, polite, and easy going. Like a casual acquaintance. No expectations, no confidences, nothing personal.
I did have a day with H's friend and all of our kids (no H) and I didn't bring up H or any problems at all. Not once. It was all easy and light.
I should tell you that it took me 3 months to figure this out, and my sitch was very heated in that my in laws were actively encouraging H to leave me. So it was very hard for me to keep quiet, but staying out of it has actually helped.