Is it normal weird playdate situation

So my four kids have a new playdate friend.He is five, but is kind of jaded. The ex is not allowed to see the kid a lot for some reason.The ex (the little boys father)keeps saying stuff to the other mother's about the little boys mother. She doesn't seem evil like he said.She doesn't want to talk about the divorce at all.She seems really shy jumpy and afraid to talk to us , but really loves the kid.The kid is really cute but weirdly protective of his mom. I heard from the neighbourhood gossip they used to have some really bad fights when they were still married and that everyone thinks she was the bad one in the marriage. and he did make a scene and get her all upset at the mall the one day. What should we do? Who should we believe?