Gail, I am so sorry you are feeling so low. This piece of advice may not make a whole lot of sense, but it does help me sometimes. I'm not saying I am able to do this all the time or that it works all the time.. But try it and see if it doesn't help some.
First of all, be your best friend. Like they've said. Rent a funny movie, do something that will bring you a smile. It'll be hard when you don't feel like it, but make the extra effort. You'll be glad you did.
Another part is to dress up when you are feeling like this. Don't overdress, but make sure you look good, or as good as you think you could look. It may seem like too much work somedays, but usually, you'll be glad you did.
More or less, take care of yourself and pretend you are happy and you'll really feel it soon. It sure beats moping around anyway.
And it never hurts to have a good cry either. Get it out and done with.
You weight will come and go, it's how you feel about yourself that matters most.
And believe me, I have my own problems with that. But my advice is what I tell myself a lot. It doesn't always work, but I try.