This is something that I've dealt with personally and seen on this forum a lot! It looks like you already have a benzo, so my suggestion is take that as prescribed by your doc. I usually keep my benzo in its pill box and try not to use it unless absolutely necessary. (Xanax works incredibly fast, so I don't see a reason to dose unless I have to).
I learned breathing techniques and also did a lot of reading on how safe flying really is. As soon as I get panicky I start to control my breathing and try to focus on something else. I have found getting lost in a movie or a book really helps.
The biggest thing that helps me with flying though, is time sober. The longer I've had sober, the less prone I am to anxiety. I fly about 100,000 miles a year and still am not fully comfortable with it though! You have ponied up to change your life and quit booze! If you have the strength to do that, you can make it through a flight sober!