Falling backwards...

Sometimes I just don't get it...I sabotage myself at every turn, it seems, and I don't understand WHY I do that. I joined a weight loss challenge at work last month; I figured it'd be easy, hey, I was already losing weight, was heading below 190. But, as soon as I joined, I gained, yes, GAINED 10 pounds! What the heck is wrong with me? Everyone comments on my lunches, how healthy they are, and I walk all over the store, all day. Wearing the pedometer at work has shown me just how much I DO walk (one day I racked up 17,858 steps!), and yet I am feeling puffy, lethargic, and let's face it, FAT. I'm tired and discouraged and feel like giving up.
Looking over a previous blog entry, I was about to break up with my boyfriend back in November; but of course I procrastinated for a couple months (can't break up with someone over the holidays, that's just cruel...). He found a job, started in December, and has started to bring in some much needed income into the house. And because of his job, he's lost 15-20 pounds in a month! He's finally weighing less than me...so of course I'm even MORE discouraged. I did write him a letter, letting him know how I feel about our relationship, and that I felt it was time to call it quits. Well, he was devastated...and then he wrote ME a letter, giving all the reasons why we should stay together. A lot of it was laced with guilt aimed at me; it was MY idea to come out to New Mexico, we used HIS credit card for the move and now he's in debt and because he wasn't working, he fell in arrears and now has a terrible credit rating. He loves me just SO much and he apologized for being so distant the past year. He's trying to make it up to me by taking me out to dinner a lot, but I don't want him to waste his money on meals all the time. I've told him, he needs to save up for a bike or some other means of transporation, since the bus system out here leaves a lot to be desired (like more routes and more run times!) and having just one car is becoming a real hassle.
I feel like I've fallen into a pool of negativity, and I want to give up, and I'm killing myself with food, all the wrong kinds and too much of it. I don't really want to be with him anymore, but now it's a question of survival...we need each other in order to be comfortable, get our bills paid on time, get enough food in the house for each other's needs, share in the chores so all of it doesn't fall on just one person. Crappy reasons to stay together, but it's all I have right now. I wish I didn't have so much pain, both physically and emotionally. I'm at a point where I feel lost and useless and ugly, and FAT, and I'm tired of it! I was so happy when I was able to buy some clothes a size down from my usual; now I'm going to have to wait to be able to wear the stuff. Frustrating, and I don't see a solution.