Congrats. I hope all goes well for you. Follow the instructions they give you. I am now 6 weeks post op and have had no problems (other than getting enough fluid down - which I hear is pretty common).
You are about to dramatically improve your overall health.
You are about to reduce your risk of so many diseases, strokes, heart attacks, etc.,
I don't mean to frighten you anymore, but this in many ways for us is a life vs death decision; maybe not immediate but definitely will impact your journey on Earth !!
I am 70 now. I looked at this and said to self: "Self - if you expect to make it through your 70s and reach 80s and perhaps beyond, you have to get this weight off. I could see more and more maladies that were hurting me more and more each day. By having this surgery I eliminated these maladies and gave myself a good chance of living to a riper old age!
Scared?
It is easy for me to say now, but don't be scared. Be excited!
You are taking a very small risk and the reward is life.