I stayed in contact with my ex who I was with just before dh. We had been great friends, same sense of humour, same interests, no bad feelings, worked in the same industry, so I thought it was great that we could be friends and keep in touch, only by text or email, we never met up as I had moved away. I told dh about it and he was fine about it.
He got married, had 2 DC and started moaning to me about his wife
that she had put on too much weight, was a nag, was worried about her newborn and refused to leave it with his mum. I was speechless. This went on for a few months. I genuinely don't know what he wanted me to say
I basically just stopped replying to his messages until they fizzled out, bar odd one at Christmas or a birthday.
I have another ex who I stayed in touch with until he began a LTR and she wasn't happy about it. That was fine, I respected that.