Not sure why my ex was talking to me about his marriage and the problems in it when he saw our son…

Not sure why my ex was talking to me about his marriage and the problems in it when he saw our son yesterday. I don't see the reason to it we don't really talk a lot wouldn't consider us friends like that. Then actually told me to not text him unless he texted me first because his wife gets jealous like I really care. I don't understand people at all.