Without experiencing the loss you and your SO share, I know how you feel. For the better part of 10 days, I had no idea if my little girl was going to survive. The hardest thing I have ever done, and likely will ever do, was give her over to God. I didn't know what His plan was but I knew it was perfect, no matter if she made it or not. I PLEADED over and over for Him to allow my wife and I to raise her to follow Him and let come what may.
My point is, no matter how heavy this burden is, there is strength in more abundance than you can possibly imagine if you resign yourself enough to give it over to Him. Let Him carry the burden, He can handle it...and then so can you and your SO.
Whatever your burden--financial, emotional...you name it--give in and give it over. Allow yourself to feel everything, don't hold it in...long. I did, until I was to the point where I could no longer take it and......well, have you ever seen one of those ugly, make everyone around them uncomfortable cryers? That was me April 27th. Ashlee's BP, heart rate, O2 sats...everything...bottomed out and they had to work fast. I couldn't handle it b/c, at that point, I was still trying to do most of it on my own (because I'm stubborn) and be strong for my wife.
Don't. It's going to come out one way or another...but giving the burden over to Him is the answer.
Here's hoping that you and your SO's family feel the peace that surpasses understanding.