Thanks everybody. There's so much incredible support and advice on this thread. I've been copying and pasting things as I read, because some parts of it will be very crucial for me to remember and keep close to heart.
I am in AA, and have looked up the local office for the city where the trial will be held. One thing I'm considering is amending my trip to only be present for 1-2 days, instead of the entire duration.
My main reason for going (I have no legal obligation and am not required to be there) is to support other family members who will be testifying. No one in my family is handling this very well...some better than others. I don't want to abandon anybody, but I also know that I am no good to anyone if I don't keep my sobriety in tact.