You know who suffered from this and wrote about it? Paula Deen for Food Network.

I think I'd ask your friend if she'd like you to get a copy from the library or something.
I was almost borderline several yrs ago. Scary stuff. I literally would make myself go places and park the car. Then go home. Then go back again and walk in the store. Then walk back out. Then go back again and walk around the store slowly, then leave. Then I go back and buy something and MAKE myself wait in line to buy it. I would literally have to do deep breathing to stay in line. It was awful.
"Baby steps" it was for me. And alone. I needed to go alone. Plus going alone made me feel less embarrassed in front of mom, DH, sister or friend. They MAY have encouraged me further each time than I went but I was afraid they would so I went alone!
When DH told me we were going to FLY to WDW 10 yrs. ago, I was panic stricken! I was afraid of planes, buses, and LINES! How would I fly on the plane? How would I get from MCO to WDW resort? How would I get on those darned Disney buses everyday??!! AND how would I possibly stand in lines at every ride and attraction? I couldn't even allow myself to even *see* myself on the rides--I was too afraid of even being IN THE LINE.
I dreaded that WDW trip more than anyone here could ever understand (cause how can one dread WDW?) but I did the trip (w/ some xanax) and enjoyed myself A LOT. Came home and planned a trip for the next yr. same time. That was a turning point in my life and one of the many positive things I associate with WDW.
Now I have Disneyitis. But that is better than agoraphobia.
Best Wishes to your friend!!!