Boyfriend choosing friends over me

I’m in relationships and my close friend, that he was friends with switched up on me and started sending big paragraphs to him calling me names and trying to get him to break up with me calling me toxic ect. He’s going to a party she’s having that I’ve been uninvited from and is saying that what they’re (two of them) doing to me doesn’t affect him so he doesn’t think he should react or be upset about what they’re doing. I don’t want to be toxic like they’re saying I am so do I have a right to be upset? It hurts especially bc this has happened before and I told him at the start that I couldn’t go through it again and I needed him to support and stand up for me