The correct answer is they were all smaller than him and less hard. Unless you keep dick pics on your phone, how is he going to prove you are lying?

just tell him no, if you're not comfortable sharing the information

Send him to each of their homes so he can ask them himself.

Sorry but these are very personal and itimate informations you shouldn't give out without the persons agreement. No one want other people to talk about themselves in such a way so you shouldn't do it either. Oh and he's an insecure control freak - run. Good luck! :)

Damn that guy must be insecure.

Ok, I'm gonna play devil's advocate here, because I've sort of been that guy. While there is indeed a possibility that the guy is incurably insecure, it's also possible that he's just trying to find out what your expectations are and why kind of quality of sex you're used to. I almost always ask girls what size, duration, position and amount/type of foreplay she likes best, and if she's got some kinks. It's not really a matter of insecurity, since I know I can do the job just as well as any other guy, but rather to figure out if there are areas where I'll fall short compared to the girl's expectations, and how best to pleasure her. That being said, asking for the size of all of your exes sounds rather excessive...

This is just the tip of his controlling ways. It will only get worse from here.

Are guys out there thinking we take tape measures into bed with us?

Tell him all of your ex's were 8", except him.

Dump him.