What is it that you are depressed about?
That stinks that your support people are just not cutting it for you (I know how that is....I'm going to have a homebirth and some of my family is not too supportive).
Try to go to La Leche League meeting! Whether you want to breastfeed or not, you will definitely find at least one mamma that you can connect with.
Get out of the house! Walk in the beautiful sun in a park or just on the street!
Drink at least 64 ozs. of water.
I don't know how old your other children are, but go to the library-there's usually some type of "story time" or some other function going on. Go to your local malls and see if they have some type of a "kids club" (either FREE or $5/year).
But definitely get out of the house! Try to get help with housework and childcare (I don't know if your children are in school full time or not). Do stuff that makes you happy! Try putting on some music and just DANCE!
GOOD LUCK! Post back and let us know how it goes!