Nmom did business with my ex after we broke up

This is an old story I just remembered coming across this subreddit. When I was a junior in high school I dated someone who didn’t treat me well, he would tell me all the time that I had no chest or butt and would tell me other girls were pretty and would talk to other girls online while we dated. I decided to break up with him and couple months later he was seeing one of my friends…yeah…she was my friend for 3 years. I eventually began seeing someone else and put my past relationship behind me. A month after I’m in a new relationship my mom randomly tells me she reached out to him and his parents and we’re going to do a service for them (can’t specify but it was for one of her hobbies). I was so upset at this and told her I didn’t want her to follow through with this. She disregarded my feelings and instead of saying “yeah you’re right thanks for letting me know how you feel I won’t follow through” she just made forced her side on me and kept saying “business is business you guys didn’t even end on bad terms” she kept telling me about the service she did and would even show me pictures of my ex and laugh when I would get upset about it. I realize now this was her narcissistic way of inserting herself into my relationship. She showed me where her loyalty lied and I felt betrayed. Ever since then I added that experience to the list of reasons I’m going low contact after I move out.