Just Need To Let It Out And Have A Cry

Before I go any further, I'm not expecting any replies to this, I'm just having a really bad day and am sat here alone in tears, and I need to let it out.
It's DH's work xmas party tonight and I've just taken him there with Erin. She was in floods of tears because she didn't want daddy to go and I had to be strong even though I didn't want him to either. I managed to keep strong until I've just put her to bed, but now I can't stop crying.
I'm 33 years old, been married for 10 years and I know DH loves me, have a gorgeous, intelligent 3 yr old DD, a reasonable job, so why do I feel like I've got nothing.
I know that the monster of depression has got a tight hold of me right now although I can cover it up most of the time, and I do try to take it into account, but I can't blame it for everything.
Everytime DH is out on his own I have thoughts running through my head of what he is doing, even though he's never given me any cause to worry. And I can't help but make digs about it to him and I know he gets really upset with me. I just feel that I don't love myself so why would anyone else?
I go to work, come home and look after Erin, then stitch and watch tv, that's my life. When DH is at home we go out for family days, but I very rarely go out alone, no friends locally, and because I hate the way I look I feel very uncomfortable in public, even at work.
I just think is this what I've got in store for the next 40 years if I'm lucky? What more do I want? I desparately want to lose weight but have so much to lose, almost half my body weight, and everytime I try I give up again soon because food is my escape, and then hate myself that little bit more.
My stitching gives me something to occupy my time, but no-one but my wonderful cyber friends appreciate it. Everytime I show a family member it I just get "oh, that's nice" with a blank expression. I often think why don't I just give up stitching, what's the point if only me appreciates it, but what would I do without it?
I know a lot of people will think that I'm having a pity party and I should pull myself together, and I know they're right, I've got a lot to be thankful for and there are a lot of people in far worse situations than me, so why do I hurt so much....
I just hope today is a one off and I wake up tomorrow feeling better......