EX's don't really suck. It just sucks that we have mixed feelings towards them. Add a touch of bitterness that things didn't work out, and it can be complicated.
Plus EX's can usually push our buttons like no other!
I thought that DZsaigirl, HBADPi, and Fuzzie Alum summed it up rather well.
DZSai girl pointed out that it sounds like the nasty break-ups were mostly mostly on the part of the girls rather than this particular boy, Jack. If he just broke-up with them, with little warning and little explanation he was doing pretty well.
Then he meets up with these girls he has moved on from, because he was dissatisfied and could tell there was no future, who say he ruined their lives! Thats a harsh indictment.
Ladies, I know men never admit it, but we are moody at times also and vulnerable.
So Fuzzie alum was probably right in saying that he was feeling low and since he had started talking to you again he decided to ask you. Or he just might have been making conversation.
But people in general don't handle criticism well. So even sugar coated its hard to take. Even more so from an EX who we have mixed feelings towards. As I said its easy for us to push each other's buttons.
Also, its kind of normal to be curious as to who your EX is with, especially in terms of marriage. There are some issues of comparison, and also a little feeling like someone might be getting away.
Email him or not. But if your criticism can be accurate and not colored by your own expectations it might actually be useful to him.
The phrasing might be tricky . . .
PS. It would have a lot of entertainment value if you if you posted the email. . .