Before I get to the heart of this message, I found some information for you regarding Multiple Myeloma and how difficult it can be to detect early.

Here is an excerpt from the article with a link to the entire site from Cancer.org.

“Can Multiple Myeloma Be Found Early?
It’s difficult to diagnose multiple myeloma early. Often, multiple myeloma causes no symptoms until it reaches an advanced stage. Sometimes, it might cause vague symptoms that at first seem to be caused by other diseases. Sometimes, multiple myeloma is found early when a routine blood test shows an abnormally high amount of protein in the blood.”
https://www.cancer.org/cancer/multiple-myeloma/detection-diagnosis-staging/staging.html
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My heart goes out to you for the devastating loss of your wife and for how this has impacted every fiber of your being. Grieving is deeply personal because no one can possibly understand what you are going through. Everything has changed.

If I may, I’d like to give you my story as a leukemia patient…from the same perspective as your wife.
When I was diagnosed with AML my husband was in total shock at the possibility of losing me. He told me that his life would be over if I didn’t survive, that he really wouldn’t want to live either. This was heartbreaking to hear because I love my husband so much and couldn’t imagine this amazing man wanting to die if I did. He is brilliant, funny, full of life and has so much to offer the world. We have an adult daughter who would then be without both parents!

So, while I underwent months of chemo, my husband and I had many discussions about his life if I wasn’t around. We talked about his potential fears, the emptiness death brings, we talked about the loss of companionship, about the changes of dynamics with family and friends…the list was endless. It helped him to know I wanted him to go on! To enjoy life and not take one day for granted. While I was an integral part of his life for 45 years and he would miss me, it’s important to continue to find value in life, to give back, pay it forward, to volunteer or whatever it takes to find meaning.

I never want to be the soul reason for anyone to stay alive! It’s so important to find hope and purpose in the face of loss. And I have the feeling your wife would have felt the same way.

When you’re ready, there is a support group on Connect for loss and grief. I’d encourage you connect with other members who have lost their spouses. It can help to know you’re not alone and that others are experiencing the same depth of loss.
https://connect.mayoclinic.org/group/loss-grief/
https://www.verywellmind.com/coping-with-death-of-spouse-2301016
You mentioned that your wife was also a mother. Are your children living nearby? How are they coping? Do you have other friends and family or church groups for support?