Welcome!
You are so very fortunate that your doctor suggested the DS. Over the years, we've seen just the opposite - surgeons not even mentioning the DS because they don't offer it, despite their patients having many comorbitidies that are much more likely to resolve with the DS than with any other operation.
The DS has the best statistics of any bariatric surgery not just for percentage excess weight loss, but also for maintaining that weight loss. This is crucial. We see new people all the time who had sleeve, lap band, or even gastric bypass who either never lost much (lap band, mostly) or who did well for a few years but either never lost enough or now have regained significantly. The DS also has the best statistics for permanent resolution of all major comorbidities - type 2 diabetes, sleep apnea, high blood pressure, etc.
You don't say what other medical problems you have, or what it is that you are so afraid of. Yes, it's a big operation, but there is no point in having any major surgery if it doesn't work. Weight not just the potential risks but also the potential benefits, and IMHO the DS wins hands down.