Sometimes we have to learn lessons the hard way. I understand you, I've had the same thing happen to me and I know how disappointing it feels. I encourage you to think of it as your chance to lose and maintain for good so as not to feel that way again. Maintenance is very, VERY difficult so don't feel defective for slipping, but don't let it daunt you too much either. You might want to check into articles about maintaining too along your journey, just to be prepared. By the way, you're still a success and I know you can do it if you've done it once before. Starting over is a sign of strength. Determination will carry you.
"I'm not in this world to live up to your expectations and you're not in this world to live up to mine."