I know I felt like you on and off for a a couple weeks before surgery. I was scared and tempted to back out, even at the hospital I was ready to run for the hills. But I didn't and I didn't have any complications with the surgery. I followed my pre op diet to the letter to ensure my best possible condition before surgery.
You've obviously researched the gastric bypass surgery, you've taken the courses and you've made the decision to proceed with the surgery. I stopped researching and reading threads about complications when I started to worry, because I knew they would scare me. Also people don't tend to start threads when everything is going well and they have no complications. I think we all go into it with that fear in the back of our minds that we will be one of the ones with complications, not just for WLS but for any surgery and that's natural.
In the end it's only a decision you can make for yourself.