My mom is freaking out.
I guess the only thing TO do is tell her you're happy with your decision. That you lived a good life up till now, and if anything did happen.....ya know? I don't really think there is much one could say to calm those fears...Maybe just keeping a brave face yourself would help her That's about all you CAN do!
My mom is pretty internet savy so I told her to do some research into the surgery, (she's also a nurse) and remembers all the deaths associated with this surgery, So i had to remind her times have changed and the surgery is safer than it was back then. AND they make sure you meet the standards before they will operate on you.... With my brother being a surgeon he's helped some to calm her, but she's really not behind me on this she keeps telling me to do this diet or that diet, I told her I need something that will FORCE me to change, I can do all the diets in the world but unless my jaw is sewn shut then I can ruin all the work...
Just dont let her fear get to you thats the hard part!