I felt that way after I had my 2nd child. My husband didn't want to do anything with me and I felt unattractive. My best friend would call me up, offer to come get me, pay or whatever we were going to do and everything and I had no desire to do anything.
This sounds crazy but I started my home based business and that changed my whole world. I'm not here to push that, but merely to let you know that finding something I was interested in that engaged me with other people did the trick for me.
I, also, recommend http://www.meetup.com. You can put in anything your interested in from play groups to horseback riding to networking to whatever you can think of, and it will pull up groups around where you live. That will give you a chance to get out and do something you enjoy as well as meet new and interact with adults. If you can think of something and don't see a group for it, you can make your own for people to join!
God is good.. He'll see you through this. You sound like an awesome person and an awesome mother. Hang in there!
Take care and God bless!
M.