Keep your focus on your kids, and ignore the ex's friends. They can think whatever they want, but it doesn't make it truth.
"Keep your face always toward the sunshine - and shadows will fall behind you."
You don't have to talk to any of them. You are right, you are there for your kids. If any of them approach you, just smile, and chat. You may be surprised how many of them refuse to talk to your wife now...I know I was, when the men from my son's hockey team started to tell my XH to screw off and never talk to them again.
WH says marriage is over: May 15, 2009.
EA#2 July 20, 2009. Legally sep: Aug 16, 2009. DIVORCED!!!! Signed Nov 23, final Dec 24, 2010, adultery listed.
I just hope they don't take it out on your kids because of their mon's stupidity.