How to solve medical problems

I'm new to this board and I am having trouble dealing with my step children's mom. I didn't expect this relationship to be easy, but I certainly expected her to be alittle more understanding especially when she is always saying how she wants to be friends with us. My first issue is the fact that I am pregnant, very pregnant and ready to drop any day now, and she is being beyond inconsiderate to us. I have been in and out of the hospital a few times with some serious complications and she has refused to get the kids until we have been there for over 5 hours. I understnad that when we have them it is our responsibility to take care of them, but we have no one to take them and so my husband has to sit out in the waiting room while I am all alone. The last time I was there I was in preterm labor, which they managed to stop thankfully, and she said that I didn't need to have him there to help me and to deal with it. He was so upset and he was there for both of her pregnancies and to do this is beyond low. Then she sent them to play with one of her younger cousins and they were exposed to chicken pox and won't help us out, this could potentially kill my baby if it comes while they are contagious. To top it off she won't admit that her son has a development issue, he is four years old and can't say any words correctly, he gets close with mom, dad, and pizza, but that's it and because of the divorce agreement we can't get him taken care until she says ok. He will only suffer more if this is prolonged and I don't know what to do.