My MOH is my sister, and she lives across the country. Unfortunately, she's no longer coming to the wedding because she's pregnant and due just 2 weeks before the wedding

This has been bumming me out since she found out the due date in January, and I'm struggling getting out of my funk about it. I'm so sad that my sister won't be at my wedding - she's my sister and we're really close! And (this is awful) I'm also angry with her because I want her to be here and she's not doing anything to try to be here. I know, I'm a horrible person for being angry with her. It's not like she can do anything about it.
I guess I'm just exhausted from the weekly phone calls with her about how she's upset she can't come to anything (shower, bachelorette, wedding) and yet there is nothing I can to do help or fix it. I've cried about it enough, and I need to accept it or something now.
How do I deal with this? And what do I need to do about her not being able to be here? Are there details I should be changing?