My ex made another email and messaged me again

its your choice but some guys do that... its all head games.. act like an ass when they get you then act all friendly when they dont.

I would delete it and just not respond. If you respond he knows you got it.

Charge your phone.
Whether you reply to him or not is up to you.

Hit that "Report Junk" link.

Say something or nothing that's up to you

Don't say anything.

It sounds like an innocuous message, but you know him and your relationship best. Will have to use your best judgment. You can reply that you are alright and, if this is how you feel, that you do not wish to speak with him further.

Be smart with him. Say, "If I was in the terror attack at all, it's likely you would have figured that out by reading the news. Leave me alone."

He's either guilty over the breakup or trying to start something again. Responding with, "no, I was one of the people killed" might be fun.

Is he stupid?

I think you should reply to him with hopes that he actually changed.