Oh ye of little faith - TRY, TRY, TRY, and TRY AGAIN UNTIL YOU GET IT RIGHT!
Stopping this habit is not an easy thing, but it's not impossible. You have to get it in your head and educate yourself on all of the SERIOUS dangers it can do to you. If vanity is easier - focus on those reasons. Go back and read the threads and you will find a TON of info out here as to what it can do to you.
You have forgotten why it is you felt so strongly about quitting to begin with. Write it down and carry it with you at all times if you have to but whatever you do DO NOT SMOKE. You've done it and you can do it again.
I had quit for 6 days and broke down when I first tried to quit 2 months before this quit. I had even used nicotrol but wasn't really consistent with it so this time I went cold turkey and said - "You know, I'm sure I'll miss it at times (of course not when around others because it stinks so bad), but I'm committed to quitting and will NOT forget that it can kill me at any time and I do not want to die."
DO NOT FORGET - look up the disfigured people or sadly the people that have lost their lives (wall of remember on the lung assoc.org board) and how badly their loved ones miss them and are so mad at a cigarette for stealing away their loved ones. Maybe it's easier to think of everyone you love soooo much and how a cancer stick can selfishly take it all away from you. I hate to sound so grim - but hey - this is reality and smoking can kill. Do not take the risk. Just get back on track and beat this thing and save some money while you're at it.

One day they won't be affordable anyway so it's best to quit now because you know the longer you do it - the harder it becomes so just do it and we're here for you.
My prayers are with you as well as my support and you are NOT a failure - you had a relapse and WILL get back on track. Start thinking about your quit date.
Laurie