Need honest opinions about putting my dog to sleep

[Avalonholly]

Hi everyone. I'm new here and to forums but, I need help making a dicision. We have a dachshund, 12yrs. old, female, that's just been diagnosed with bladder stones. The Veterinarian also said that she has the beginings of cateracts and her teeth are wearing down or in bad shape. We've had her for a little over 4 yrs. and I took her in after trying for about 3 yrs. to get pregnant but couldn't. Long and behold, I got pregnant, and unfortunately haven't been giving Mercedez (the dog), as much attention. My two older children and my husband are the ones in charge of walking her but, I pay for all the Veterinarian bills, most of her food, and grooming.
For the past 2 or 3 months now Mercedez has been peeing in the house. We have beige carpet and my husband's fed up with her. He thinks I should skip the surgery that will total to about $400.00 in the Humane Society. My heart tells me that's wrong, because she's not terminally ill, it's not an outragious price, and like my mother's been saying, it's said that she was my companion before the baby came into the picture and now we're going to get rid of her because of something that can be fixed. Another thing is, I've heard that when dogs go blind, they can still get around well with their sense of smell.
What are the opinions here? Should I put her to sleep? I don't mind someone adopting her, cause financially we're tight right now, but no one's wanted to adopt her. So I feel that we need to keep her until she passes away of natural causes or another problem in the future, cause I wouldn't pay for any second surgery in the future. It's just my husband that's putting preassure on me to get rid of her. HELP!