stormageddon, what does your fiancee think? or is he not fussed?
Is your wedding big or is it something small and intimate?
Honestly, if it was me, I wouldn't invite him. Our wedding is small and intimate so it's only our close immediate friends & family....if your wedding is something small and intimate and he gets offended for not being invited, just apologize and say you had to stick to a budget and unfortunately, there were a few people you'd like to have invited but couldn't. Maybe just write back to him saying "aww Thanks! We're getting married on (date). Can't wait!!" ....and leave it at that?
If your friends get upset that you didn't invite him, explain that you're on a budget and you the guest list was made on a fine line.....if they're going to ***** about it like school kids, clearly they aren't "friends".
But if you don't mind paying for him to be at your wedding, then by all means invite him

the more the merrier!