Detach yourself now. I realized that if I were to not see any of my sisters ever again, my life wouldn't change. This has made it easier to deal with them. This doesn't mean you "disconnect" like Scientology would prescribe. This just means to prepare yourself for the real and distinct possibility that they may not be here tomorrow. Most relationships are transient in nature, based primary off of proximity.

It's not especially pleasant, but it makes disagreements much, much easier to deal with. Death or other separation is easier to deal with too.