Should I write-off my cousin and never have anything to do with him again?

[Rory]

We were good friends and spent a lot of time together since we were both little even though we go to different schools. He is a year older than me, I'm 15, he just turned sixteen yesterday, and we were always cool, even when both my boyfriend (who he knew) and I both came out a couple years ago, he was ok with us that we were gay. So this year, like the last couple years he invited both me and my boyfriend to his party, with pizza, bowling, and about a dozen of his freinds. When we got there, I saw my WORST enemy from MY school there with the rest of my cousins friends, who became friends in the last year with my cousin, but never knew we were related, or even knew each other. This guy is a total homophobic @-HOLE that I HATE! So, he walks up to me, and asks me what I am doing here, I told him I am at my cousins party and ask him what HE is doing here! He walks over to my cousin, and asks him in front of everyone, if he is related to "that F@G?" My cousin said yes, but he wasn't invited and did not know what I was doing here. I couldn't believe it, I just stood there for a minuet until my boyfriend pulled me out of there. We left the building and started to walk home, and called my sister to pick us up. I have a lot of first cousins, but was closest with this one, at least I thought. I already have two older cousins I wont talk to or even look at when we have family gatherings because they have a problem with me being gay. But he is close to my age and never had a problem with me until now. I tried calling and texting him to ask why he did that, but his silence is his answer. I consider this a stab in the back. Why should my boyfriend or I ever have anything to do with him again?