Wow! Does this ever sound familiar? When I got married 20 years ago, I had a cocker spaniel who'd been my "baby" for 7 years. My husband never liked her, but I loved her. When our daughter was born a year later, he demanded that we "get rid of" the dog. It was either him or the dog... for the baby's sake, yada yada. So I gave her to "a nice family" whom I never heard from again. Twelve years later, when my second baby, a son, who had been begging for a dog for several years, turned ten, we adopted another dog--a big one who my husband would also love. Well, shortly after that, my husband left me, with the dog, of course.
Now I'm paying for all of those dog expenses you named and need new furniture, carpet, etc, because of the extra wear and tear. Our dog, Grace, is very well behaved and sweet, but I just don't have time to take care of a dog, walk her, clean up after her... you know. And I don't have the money to put into her care. We've had her 8 years, and my son who begged for her is now leaving to go to college, and Grace is staying.
I've had the same thoughts as you for 8 years, and it would have been so much easier to adopt her out 6 or 7 years ago. I've grown to love her and would really miss her, but am I even being responsible to keep her? Food for my kids? or food for my dog? I've put ads in the paper several times over the past 5 years, but have gotten to takers. My youngest son, who will still be home for 3 years, loves her, too.
So, my opinion? You should probably give the dog away, and not get another one. They never get easier, in my opinion, and I imagine it getting lots worse as they get older and need more health care. Good luck!