Julia, what you are saying is that his whole family is crazy, and you are perfect. If this is true, then there really isn't much you can do to remedy the situation because you have no power. You can get used to spending birthdays and holidays by yourself.
On the other hand, if you examine your conscience and find you DO bear some responsibility, that also means you have some power and can work towards repairing this situation. You don't have to love these people, but you should certainly be able to make nice for long enough to prevent your exclusion from family events. Honestly, it shouldn't really be all that hard.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?