Always go to the source. If you want to know something about your ex, ask HIM.
My adult kids are in contact with my ex (their dad) and his wife. I'm curious about how it's going for my ex and his wife (particularly from the wife's perspective) but I would not ask my kids to report on this, it is not their place.
I don't have the kind of relationship with my ex, or with his wife (whom I've met a few times, and like her, and am tempted to tell her she could do better lol) to ask them, so, I just don't get to know. It's okay. Their relationship has zero effect on my life.
On a related note: my mom, who is wonderful but very nosy, sometimes asks me to report on the state of my kids' marriages. But I don't. I tell her to ask THEM if she wants to know something. If I DID report on them, to their grandma, that would be a betrayal IMO. They are adults and can speak for themselves.