Mtn,
Dealing with BIG FEARS was the absolute HARDEST thing for me in early sobriety. I was like you--I didn't want to drink, but I didn't know what to do with myself instead.
I think it is great that you posted how you were feeling, here. That's exactly the right thing to do.
I can promise you that it gets easier, with practice, to deal with scary stuff without picking up a drink. Every time I did it, it got a little bit easier. The fear won't kill you--at least, if you don't drink it won't.
I don't know how you feel about prayer, but some prayer or meditation with breathing can help calm you down. You can't control what happens tomorrow in court. That's a given. What you can ask for, though, is that you be given the grace to accept whatever happens. If I recall correctly, you weren't charged with assault because the driver didn't want to press charges. In all likelihood (and I know something about how things go in court), you will have to pay a fine, and possibly have to participate in an alcohol evaluation and comply with any recommended treatment.
It's probably (I'm guessing, here) more of a blow to your ego that you are in court for something you are ashamed of than it is a real fear of serious consequences. Remember, nothing like this ever has to happen again. That was then, this is now. You are making big, important changes in your life. That's something to feel good about.
Someday this incident can be something you look back on in gratitude--that you got a hard wakeup call that you needed, and nobody got seriously hurt.
Hugs, it's all gonna work out, so long as you keep doing the right thing.