Try not to be so hard on your self. We have all gained and lost and gained and lost. I thought the same thing as you, I can lose this on my own. My friends are mostly nurses and did not encourage my surgery choice. But I have to say that it was the best decision I have ever made! I feel great!
I used to say I can't hit 200, then it was 250 and my final straw was hitting 300. I'm mad I let myself get this big too. But we can't go back we can only move forward! Don't look back at why you got where you are. There is help in surgery to get you to where you want to be. It's not easy but it is worth it!
I had my surgery on 4/17 so only 12 days ago. I have lost 50 lbs since Dec 30. When you finally hit the point where you are tired of the weight you will be strong to go thru this process.
So get positive it helps:) and good luck!