Bill, I too feel your and your wife's loss, I have had to bury or put down several pets, and just like everybody here, I get very strong allergies that make my eyes water. When I 1st started into adult life I had a big dog complex, my 1st dog on my own was an Akita, beautiful dog, strong as an Ox, interesting as hell, but died of heartworms at 2yrs old, I blamed myself. Had several German shepherds, australian shepherds, pit bull mix, and my current oldest, a Basenji. German died at 7, australian died at 14, My Basenji is now, 12, and has a pancreas condition, that she had from birth, it does not work, but we add an enzyme to her food, that allows her to assimilate her food, and she is fine, except she is a Basenji, fiercely independent, more like a cat than a dog. I inherited 2 dogs, a chihauhau male, who is really good, I grew up with them and hated them as they were always barking, but he grew up with the Basenji's who don't bark, and only gets vocal when someone comes to the door, and that I like, he is a very loving 10lbs of muscle. The next came from a cousin who died and she is a miniature Dachshund, she is a very loving girl, and very old, has little tumors that come and go on her belly, never complains, except for when she wants attention, 5 minutes later, she is fine. They all seem to know my moods, vocal or energetic when my mood is good, and then go quiet when something is not right, The chihauhau, is the 1st jump in my lap when I get mad and yell, he is the moderator. So I have learned to love little dogs, they live longer, love hard and my dachshund, although old likes to fetch but is not as fast as the Chihauhau, so play with her alone, it is so funny watching her go through 2-3" grass. I have already made my choice for next dog, Border Collie, or perhaps a Jack Russel.
As to cats, never had any use for one, until, my wife bought one at a church bazarre, let her sister keep it for 2 weeks because she knew my attitude, then brought it home and OMG the fight was on, it hated me and I hated it, it ran up the curtains and of course scarred them to get away from the dogs, hissed at me, genuinely unfriendly, then the weird happened, I came home from fishing, and just put my poles in the living room, against a corner, with the lures ( a mepps spinner ) anchored to the reel. Sometime later the wife calls me, the cat bit the shiny lure and the treble hook was through the lip, she had him wrapped in a towel. I cut the hook, and got it out of his lip, from that day forward, that cat was mine, no hissing, just love, they say you cannot train a cat, and they are probably right, like a cattle dog, they know their part, and this cat, the runt of the litter, my wife named Hercules, which is a great name, in the end, we just called him Q, I would tell him when it was time to go to bed, lets go to bed Q, and he would go and lay down at my feet, after my nightly reading, I would say Q, time to go to sleep, and he would come up and sleep on my pillow. Had 3 cats since, neither held a candle to him.
My advice, fill the void, but maybe with a smaller longer lived pet, My Favorite uncle always had pomerianians, and named all the males pepper, so as 1 passed, another took over, kinda thought that was weird but made life simpler.