You haven't let anybody down and no sense in beating yourself up about it. It's not how many times you fall down, it's how many times do you get back up!
So keep trying. If you really want it, you can have it.
When I quit smoking I kept trying to quit until I finally did it... cuz I knew smoking was a stupid habit. The same with the drink. I must have quit a dozen or more times before it finally worked.