Long story short I (23F) got invited to a concert by some of my friends. I accidentally purchased an extra ticket and invited my cousin (23F) to come with me. We did not go to the concert due to a medical issue on my end. My friend group invited me to go to a second concert with them in a few weeks, and told me to invite my cousin. My cousin brought up this plan in a generic manner in front of another friend group. Someone else in this group (23M) decided he would buy a ticket and we can “all go together”. The issue is I do not want him intermingling with my other friend group - he has substance abuse issues and has “dark” humour. I do not want him making off handed “jokes” to this group. He also gets upset when we are in a group setting if I don’t “pay enough attention to him”. AITA?