I have 3 months to go for my surgey. So I can't say that I have all the answers or anything, but I think what you are going through is completely normal. Its sounds like you just have cold feet. Just stick with it, it will all work out in the end. As far as you getting to skinny I have been watching youtube videos and almost everyone that I have seen looks completely healthy. I think dying is a valid fear. That is a risk that any surgery patient takes, but its very rare. How I overcome that nagging question is by asking myself "what is my risk if I don't have the surgery?" Diabetes, high blood pressure, heart attack, or just being fat for the rest of my life. I am 30 years old and have already missed out on so much. I don't want to miss anything else! With that said my fear is that I'll have the surgery and somehow find a way to remain fat. I'm scared that even if I lose weight it wont get me where I want to be. Size 14 would be super model skinny for someone like me. I'm also scared of lose skin, but I tell myself that it can be fixed with surgery.
You said that you wanted to ride a roller coaster again (me to), you said that you wanted to be flirted with again, and that you want to be able to sit without thinking you will break something. I've been there and done that funny now, but devastating at the time. I'm talking "Shallow Hal" moment lol when she was sitting in the crowded restaurant and broke the chair. What I would suggest is to make a list of everything that you want to do. Then when these fears start popping into your head pull out that list and it will remind you of how the surgery will help you get there.