Breaking up

Is it enough to break up with someone since they started hanging out with your neighbor whom you’ve never gotten along with I. The four years you have lived in your apartment? The reason we don’t get along is unknown, in all honesty the neighbors just out of random been threatening and stealing and causing drama since the first day of me living here. And I’ve tried to explain to the boyfriend of 8 months how it bothers me but I turn out to be the bad guy. But I just really dislike them hanging out cause I know how the neighbor is. Me and the boyfriend had recently got in a fight and broke up for about a week and the neighbor was at his house when I stopped by and to make it short all he did was talk smack to me and got in my face. For literally no reason. And nothing was his business.