I feel like I'm going to drive off my pregnant cousin on our culture's biggest holiday
Are you going to drive only her off?
The whole family, they were a huge set-back for me during those holiday days.
Some people can be annoying but it is not good to exclude them especially on a huge event. People are allowed to celebrate and have fun and you shouldn't block them.
Why can't I? I'm not turning my back on them and I'm going to have fun despite their presence. In fact, I'm going to enjoy the time I've got with them by showing them how much of a failure they are. It's my holiday after-all.
While it is your holiday, it's not just yours and there are others to celebrate with! Celebrating with others is a time for joy, not anger and exclusion. Why not take this time to reconcile with them all?