first of all to you
sounds like everything hurts right now. I second the girls saying it would be good if you could talk to someone.... sometimes people with an outside perspective can see things more clearly than people we know... and sometimes just having them acknowledge that you're going through something really difficult and still coping and looking after your DD can be just what we need. And if there is something more they can do, like referring you to services or stuff that can help, that is even better.
About your friend, she is your friend because your hearts are on the same level, not because of money, or marriage, or babies, or any of that. As Deb said friendships of all kinds flourish, because people's hearts are in tune. And everyone has seasons in their life, sometimes they face hardships, other times they enjoy success. Friendships are there for all those things.
Take care of yourself, thinking of you xxx