"She panicked when MIL turned up and couldn't face speaking to anyone because she didn't know what had happened to the babies. She said she stared at the floor in silence until I woke up."
So your own mother let you down, as well as your husband? I was in agreement with you that your MIL is selfish, I still am. However I have changed my stance because your MIL was only allowed to sit in your room with you because neither your mother or your husband could shake themselves out of their own daze to stick up for you. THEY failed you. Not your MIL. What happens if there is another medical emergency with you later on down the track, will your DH still be too 'dazed' to stand up for you? Will your mother just stare at the floor?
I know think you are directing your anger at someone you don't have a bond with, because it is easier than facing the fact that when push came to shove, in a moment of crisis, your mother and husband crumbled and could not be your advocate. Your mother knowing and doing nothing at all changes things. It changes things to your story entirely. Ultimately, you had the two closest to you, who did bugger all to advocate for you.
You were failed by your own mother, and by your husband. The MIL is a red herring and an easy target. If my mother stared at the floor and did nothing, I would never, ever, EVER forgive her. In fact, I think I'd almost go NC with my mother over that.
At least now you know you can't ever rely on your own husband and mother to advocate for you. They'll fold and be 'dazed' when you need them to pull themselves together, for YOU, they'll put their own 'dazed' feelings above your needs. I feel sorry for you because your closest are not capable of even going on autopilot for you, it is trying times that shows what people are made of, and people who should be there to advocate for you, cannot do it. Maybe you should hang onto her, as irritating and selfish as she is. She seems the only one who doesn't fold.