life of a loner

I had a fallout with one of my ex girlfriends last night who in my opinion had no right to interfere in my doings. we were at a friends house for a party,as we are all mutual friends i met a lady i never laid eyes on before and we started chatting but as it turned out the young lady in question was a family member of my ex and i did not know, not that it really mattered to me because my x girl had her new boyfriend there and we broke up 6 months ago and was still friends so i mean who gives her the right to dictate to me and tell me who i can and can't date or see.In the end the two lady's went at each other and it did not turn out so good for neither of them.in my opinion my x had no right to interfere in my or someone elses life she has a life of her own and i do not interfere in her life so why does she try and interfere in mine????.At the end of the day i am a single guy and their behavior was not in the least lady like,they just made fools of them self's in front of friends and strangers.maybe it was the beers and wine talking, but from my point of view a person should be held accountable for their own actions and be responsible for what they do.I hope that they have learned a lesson from their stupidity.Because due to their actions and behavior i don't think that they will be invited to another function again.