re: the fear of dying = banish that thought. You're not going to die. Weight loss surgeries years ago were dangerous, but they just aren't anymore. Techniques have vastly improved, and these have become very common, routine surgeries. They're really no more risky than any other abdominal surgery. The mortality rate on gastric bypass is 0.3 %. It's even lower for sleeve. So you have at least a 99.7% chance of not dying. Those are excellent odds. Better odds than hip replacement surgeries, and they do those all the time. Honestly, you're more like to experience complications and death by remaining obese than you will be having the surgery.
the pre-op diet is tough - and the first few weeks post-op can be tough, too (although in many cases, the pre-op part is worse). But you'll be through this before you know it. I would have this surgery again in a heart beat. No regrets whatsoever.