My relatives treat me with disregard?

My relatives(mainly cousins) pretty much treat me like an outsider, yet whenever they come into town for a visit(of course, I am usually notified at the last minute), I am expected to drop everything and go visit them. I feel like such a dummy when I do it, but if I don't, they'll try and make me feel like more of an idiot. I know they thumb their nose at me, because I am single, don't have children, or a big career. I end up just sitting there looking and feeling like such an outcast. I can also tell by the way they converse with one another, that they keep in touch, yet I have tried a few times to contact them via internet, and they acted like I was bothering them. I know I don't have a lot in common with them, and that's okay, but I don't like the manner in which I am treated whenever I am around them. So, my question is, should I just visit them(it's only for dinner), or should I not go, and then have to make up some lame excuse. Either way, I'll be made to feel and look like a dummy. Also, what's the best way to act around people who treat you like this? Thanks in advance for any helpful suggestions.