How can i not help feeling upset and would I be wrong for breaking up with him over this?

Well my boyfriend celebrated his birthday 2 days ago but I couldn't come because I had to move things out of my dorm. Every year traditionally he takes his best friend and his girlfriend and his brother, mother and father out to dinner. Well since I wasn't there in place of me he invited his ex girlfriend and his best female friend (I don't mind the female friend since she's cool but I have issues with who else he invited). His ex gf doesn't like me, she's a liar and manipulator and he knows we don't get along and that I would be upset if he invited her to dinner but he did anyway. He didn't tell me before I left that he was going to invite her but I had my suspicions. Instead he called me 30 minutes before they left for dinner to break the news. Then he acted like I didn't have a right to be upset because we agreed that he could hang out with his ex as long as he was truthful and told me where he was and who he was with. He lied to me in the past about hanging out with her and drinking at a party and he also went to a dub step club with her behind my back. And I know that things he's done in the past are fine examples of emotional cheating. I just really don't know what to do and I just don't know what to say because this feels like a total slap in the face. What do you guys think about all of this? Do I have a right to break up with him even though it's his birthday?