Driving Long Distance

I've always had an irrational fear of driving. Not sure why, but it just makes my panic disorder come at me full force. My boyfriend & I are moving out of state. From Maine to Tennessee; about 1,200-1,300 miles. I'm 21 weeks pregnant but will be 23 weeks when we take off. I'll have my brother-in-law who already lives down there lead us in his car but I'll have to drive my own down with my boyfriend. I'm so scared that I won't be able to do it. I want to go so badly but my mind is trying to talk me out of it. Does anyone have any advice to help me make it through the 2 day trip??