OP, i was where you were, 7 years ago. my marriage was in the toilet, i weighed 374.5 pounds, and i was MISERABLE. for me, the wake-up call was my uncle's death-he weighed over 500 pounds, and had an abdominal aneurysm burst. my mother called me from the hospital crying, as she waited for the doctor to come in and disconnect the ventilator from her brother, begging me to do something, because she couldn't go through this again. now mind you, over the years, i've been on every diet you can think of: weight watchers (twice), nutrisystem, slim fast, deal-a-meal, you name it, i did it. as fire dancer said, diets just don't work. you have to change your life. the week after my uncle's death, i saw a gastric bypass surgeon and two months later, i had my surgery. i lost 190 pounds, and while i will never be thin, my quality of life is 1000% better. before surgery, i couldn't even walk to the bathroom without getting winded, i had to cook sitting down and wash dishes stooped over because my back hurt too bad to stand upright. my husband had to help me shower, buy groceries and run all errands, and (yes, i know, this is TMI, but it needs to be said) even help me wipe myself. i had no life, and the surgery gave me my life back.
i know, surgery is not for everyone, and it may not be for you, but the point is, you have to be ready to change. you can't do it for your daughter, or your husband, you have to do it for yourself. don't think of it as losing 200 pounds, think of it as changing your life for the better. as i said, i've been where you are now, and i'm sorry this post was so long
ETA: i know, some people see weight loss surgery as an easy way out, but i assure you, nothing about it was easy. i still fight my food issues every day. surgery changes your body, but it can't re-wire your brain.
Gather as much support as you can and know that you always have a choice and are never helpless in life.
