you shared all of your secrets with her - that was YOUR choice. And it is her choice as to whom she wants to share her secrets with. Just because you are friends, even good friends, or even "best friends", does not mean she must share all her secrets with you. She has a husband and she may quite naturally turn to him. Some things (like the miscarriage) are maybe things she wants to keep to herself or only tell to select people and that is HER CHOICE. The fact that you choose to share your secrets with her doesn't automatically mean she must do the same.
What do you do? What do you want to do? You can continue to be her friend if you want to, and try to come to an understanding that she has a lot of other things going on in her life so if she doesn't make as many plans with you or if you have to be the one arranging things and contacting her - well, you can accept that as a new factor in your relationship or you can pull away. It's up to you and it all depends on how much you value the friendship and like her as a friend. She said you are still her friend and "friends same as always" so if you can put your hurt feelings aside, accept the fact that her secrets are "her secrets" and carry on, maybe taking time to get your own life in order and fill it out a bit (job, other activities, hobbies and interests), then do that but I think you'll have to accept that maybe your expectations of the friendship are different from hers and you need to readjust your thinking a bit.