Condolences on your loss. It's heart breaking to lose a spouse and 53 is way way too young.
My father passed away unexpectedly at 63. My mom knew absolutely nothing about their finances and I had to sort through a ton of stuff to ensure I captured everything. The pain about this is that you're never 100% sure you got it all, as they say, "you don't know what you don't know". Thankfully, there was a will and everything passed to my mom either immediately or when the paperwork was sorted out. Also, this was 1991, so no online banking and no auto withdrawals of funds to pay bills. Everthing payable came in the mail.
Spouse and I have had doomsday file for a number of years where everything finance and estate related is in one place. Lists of investments, accounts, pension incomes, routine payables, credit cards, house documentation, wills, POA, funeral details, password manager p/w, etc. etc. Kids know where it is as well. So, if I head off to OH on a bike trip and don't return or we're both in California when the big quake hits, the survivors can pick up the pieces and continue on with the least amount of hassle.
Ensure all of your registered accounts have benificiaries or right of survivorship and that joint accounts are set up properly.
One note here is to not rush and advise banks or pension providers of the death until you are certain that you have funds to run the household and pay bills for 2 - 3 months + have proper bank access. My father died at the end of the month, on the 28th, there was the funeral and then the search for documentation began. Pensions were paid on the first of the next month and then again a month later. By that time I'd found all of the documentation, funds in accounts and knew there were no financial concerns. At that point I wrote to the all the pension people, explained the circumstances, that I was new to being an executor and asked them to submit their calculation of any pension to be repaid, if any. Their responses trickled in over the next month and I cut them a cheque as required. No hassles.