Failure is only failure when we fail to get back up when we fall down. You are back up and posting here. That shows me that you are by no means a failure.
It took me hundreds of times stopping drinking only to fall down and have to get back up before I finally found any length of sobriety.
The key is to keep getting back up, never quit. You can do this. Each time you fall gives you a bigger picture of what pushed you to the ground. That gives you the knowledge to see that coming next time and hopefully avoid the obstacle.
Take care and remember you are not a failure. This disease is a killer and it is tough but not impossible to beat.