I wouldn't recommend Xanax unless the OP already takes it or is willing to get the Rx immediately and do a few "trial runs" on her own, on the ground. I cannot think of anywhere worse than on an airplane to try out a new Rx medication--- even if you're driving a car, you can pull over, get out, and sort yourself out. Ambien is "worse" than Xanax this way, with some folks having feelings of disorientation, panic and paranoid dreams, but none of the Rx stuff is 100% predictable for all people. (Just ask my sister who spent the last 4 hours of a TATL flight in the lavatory due to a Rx freakout, fortunately this was pre-9/11 so once we explained to the FA's why she had barricaded herself in there, no one fussed.)

I'd not recommend to replace Xanax with alcohol, partially because the OP could be kicked off during boarding if she appears to be actually drunk (which, if she is in hysterics at the thought of flying, could be mistaken for drunk, especially if there is an alcohol smell), and partially because extra bathroom breaks are often required when alcohol is present, making it harder to actually sleep, should one calm down enough to sleep.

And I'd definitely not recommend grabbing a stranger's hand-- there are just so many ways that this can go wrong.