My ex-boyfriend and I broke up about a year ago (amicably) and have been friendly since. I was setting up an activity with a group of people, most of whom he knew and got along with, that I thought he would be interested in. I had originally set the same activity over the holidays but everyone was busy so it was rescheduled. When I originally set the activity, he had said maybe so I thought it safe to invite him again.
I should clarify that there is one person within my group of friends (more an aquaintence) who ex does not like (other guy is good looking and pretty sucessful. I think there is some jealousy at play. They knew each other before we met, within the same social circle). He has tolerated this person before and because said individual travels frequently his attendance was doubtful.
I received a scathing letter (and rather hurtful) from ex that he was insulted to be invited to the same activity that other guy was invited to. I actually expected him to say no if the other person was attending but I thought being insulted by an invitation was kind of... special.