Hi, I am so sorry for yours, and your wifes loss.
My Mum died suddenly in August 2017, yes she was 89, but like your mil she wasn't expecting to die, I had to do CPR on her, and failed. I had been with my husband for 25 years prior to this, like I suspect you do, he loved my Mum and felt her loss enormously too, however for me it was not good enough, I remember screaming at him " don't you realise what's happened to me " amongst other things, I had kept it together, but for my Mum, i am sure your wife feels like no one knows what she is going through ( they don't exactly ) and it's a hard long road with lots of ups and downs, even now my heart is breaking still, but eventually i have stopped expecting ting the world to feel like i do, and my husband and i have settled back, he listens with my continueous grief and stories, and slowly we are getting there.
The upshot is, which I am trying to say somehow is, I have been and still are where your wife is, it hurts, you get angry, emotions everywhere, despite my behaviour my husband was my constant, he was just there, yes we had arguments but we are okay, it's just baby steps,
Sending you both hugs and prayers