As a pastor, I empathize with your loss. While a spouse is very different than family members, I lost my father and grandmother within a year of each other. I had to handle both estates alone.
What I learned is this: at first, just give yourself time to grieve. If you start uncluttering and it upsets you more, that's not a positive result. If you really want to get started, just get rid of the things you KNOW you can do without, that are easy - for me it was medications, old papers, clothes that I knew I didn't want or need. Some (like my fathers) I kept because I wanted to be close to something he owned and wore.
Second, over time, you will be able to let go of more. Don't be frustrated by not being able to let go of certain worthless objects - I just now got rid of an old mirror from the 60's that was on my grandmothers door. She died three years ago. I was ready at certain times to say goodbye to certain things.
Third, this will help the most I hope: once you've grieved for awhile, recognize that the objects you own that are his are NOT his love, or your relationship. They are simply things. Once you can say "This is not him, or his love for me. That will always be there, and I don't need to hold this thing for that."
What I've kept is two small boxes - random collections of stuff, but those things which form the happiest connections to who they were. I love to go through the boxes now, because they make me smile and remember all the times we had together, and the stuff is no longer a burden.
Good luck. God bless you.
