Fear of flying

Anastasia
So I am a pretty seasoned flyer. I've flown abroad about 7 times and in the US about 10 times. Tomorrow I have a flight back to the US fromZurich...and I am completely panicking. I've always been a little nervous of flying, but this time is different. I haven't slept for 2 days, I've been having panic attacks really badly. I can't stop crying. I think part of the reason is that I am leaving my fiancé behind until Christmas and I am heartbroken on every level. I'm scared to be away from him, so far. I'm scared of him being safe, and keeping myself safe... I'm overthinking everything. I don't know what to do or how to make it better. I do have Xanax I can take. Will that help? 
Please, any suggestions would be greatly appreciated. I've never felt so terrible