Does Gastric Byp surgery really work?

I am really over weight. Well actually i'm morbidly obese. I am 25 years old, and i weight 230lbs and i'm only 5 feet tall. I am what is known as an "emotional eater" I've been this way since i was a kid. When i'm really sad or depressed i eat, i've been to therapist and that hasn't helped at all. Now i am a mother of two of the greatest kids ever and i really want to see them grow up. I was wondering if gastric byp surgery really works well. Members of have done it al lost a amazing amount of weight and looking amazing. But a friend of mine did the surgery and has gained a large amount of it back. I don't want to be fat anymore.. but it almost is the easier thing to be. Does any one have any good advice on it.. or is it a quick weight loss but in a few years i'll be back to square one.