I've gotten freaked out before every surgery I've ever had, and I've always sailed through just fine.
Don't get fixiated on the horror stories, as those are rare. They seem more common than they really are because people are more likely to post when they have problems than when they don't because they're looking for support or advice. Of course, those things do happen and it's good to be aware of the possibility, but again, they're pretty rare.
the mortality rate on RNY is 0.3%, and it's even lower for sleeve. So you have a 99.7% chance of not dying - which are excellent odds. Major complications are also rare. Many of us don't have complications with these surgeries - and for those who do, most are minor and "fixable". I also contemplated surgery for 10 years (maybe longer), and I came to the conclusion that I had a much greater risk of complications from staying at over 300 lbs than I did with having the surgery.
you always have the option to cancel or postpone if you're not ready - but I did go through with it (obviously) and am so glad that I did.