Chickenpox in adults.. questions?

My son ended up getting chickenpox. It's day 2 and he's mostly fine, just warm and itchy. Our friend was hanging out with him during the 2 or 3 days leading up to the first spot, so exactly when he was getting contagious. I told her casually and she told me she was unvaccinated and hadn't had it yet. So I went to the internet.

I am worried about her. Even though the mortality rate is very low (the sources I've seen say between 0.02% and 0.05%), and she's very healthy, and young, and so on, everything I read about it seems absolutely hideous. Reading words like encephalitis is terrifying. I have told her as soon as she can go get some stuff from the doctor for it and let them know she might have it.

Are there ever "normal" cases of adult chickenpox or does everyone feel like they've had a brush with death? Is there a chance she didn't get it? I am freaking out maybe more than I should as the doctor in our family is telling me to calm down and that it sucks but she'll be fine and complications in healthy adults are rare. But it feels like he's just trying to make me shut up :(