One of my exes likes to inform me of how well his current relationship is going. Which is, okay, great for him. Congratulations. That’s wonderful. 

We’re good enough friends that I guess it’s okay for him to tell me stuff. I care about him and I love him very dearly on another level than what was sort of previously appropriate. So, fine, he’s entitled.

But I’m really never totally sure how to respond. What the heck is the appropriate thing to say to someone in this sort of situation?