First of all - cast that shame away. It's not going to help you lose weight. Losing weight is the best thing you can do for your body because you love your body, it's the ultimate gift.
Second of all - tell us what you were doing to lose weight before. Calories, exercise plans, food plans - the works. I am sure we can help you determine what went wrong and how you can improve. There's always room for improvement, I've been tweaking my plans for years now and I'm still learning.
Third of all - YOU CAN FREAKIN DO IT! Believe in yourself! You sound so fed up with your situation so use it as a catalyst to begin a life where you can be proud once more and never give up!
Goal 1: Halfway point to borderline Overweight/Healthy BMI~ 165 lbs
Goal 2: Weight when I was 17 ~ 159 lbs
Goal 3: Borderline Overweight/Healthy BMI ~ 150 lbs
Goal 4: Lightest weight ever! ~ 148 lbs
Goal 5: Lighter than Boyfriend ~ 145 lbs
Goal 6: Halfway point to Healthy BMI ~ 140 lbs
Final Goal: Midpoint of healthy BMI range (21.6) ~ 130 lbs