Was I wrong for this argument?

Me and my boyfriend got into a huge argument because he accused me of starting an argument with a guy. The situation was that there was a guy who has been STALKING and harassing my sister for years after they broke up. He has posted nude videos of her and sex tapes, calls her from different numbers and makes fake accounts just to get in touch with her, posts nasty and horrible comments about her and shows up to park at my house at all hours of the night. He has sent pictures of guns and threatened to harm himself and her and anybody she wants to date moving forward. My sister stayed with me at my house so I had to deal with this dram constantly. We called the police many times but they basically said until he actually tries to hurt somebody they aren't gonna do anything. I have only met my sisters ex boyfriend ONCE. So finally my dad got fed up with her harassment and the police doing nothing and he confronted her ex and they got into a altercation. So my sisters ex boyfriend had a brother. I did not know the brother at all. But he was on the phone with my sister sending threats saying he was gonna come over, describing my house and saying he had pulled up to my house before but we weren't home. The brother said he was mad and that his brother was confronted and in retaliation he was sending threats. So I overheard the phone call and told the guy to stay the fuck away from my house. I was threatened and scared for my safety and the safety of my family and the guy was basically jumping on a bandwagon to continue to harass and threaten my sister and my family even though I don't know him. My boyfriend came over to watch the house that night but today we had a huge argument because he told me I started the argument by inserting myself in the conversation. This man was THREATENING to come to my house and the police wasn't doing anything about it and the fact that my boyfriend said I started the argument was really offensive.

Was I wrong for this argument?
Post Opinion