Need advice about SO's kitty...

So we've been having this problem lately of SO's cat relieving herself all over our house. She's not just peeing, she's pooping too. He keeps their (we have two of them) box clean, we haven't changed their food, and they get filtered water (because I'm awesome like that, lol). I'm convinced that this is a behavioral thing, and that she's acting out because she's mad at him for something. Either he's not giving her enough attention, or maybe she's caught on to the fact that the baby is coming SOON. I am a firm believer that animals have feelings just like we do. It is possible that she has some sort of urinary infection, of course, which would explain the random urination. But the pooping everywhere... I can't really find an explanation for that.

Here's where the advice is needed. NEITHER of us have enough money to get this poor baby to a vet if she indeed DOES have some sort of infection. We can't afford to get her treated. I am a firm believer that if you can't afford to take care of an animal, don't have one. I know he loves his babies, I love them too, and it breaks my heart thinking that we might have to give her away. But either way, I know what needs to be done here. I'm not the one that needs convincing, he is. How do I get SO to look at this logically? If she is indeed sick, like with a urinary infection, she could die if it's not treated. And then all we're doing is prolonging her suffering because HE can't give her up. And even if she's not sick, I am NOT gonna have her pissing and smurffing all over my house when this baby gets here. So what should I do here? Try to find ways of making her happy (which I don't see possible, she hates kids and there are about to be 6 of them in this house, and she's not allowed in our bedroom anymore), or try to find a way to convince SO to relocate her? I love SO, and I love the cat. But something's gotta give here. HELP!

Sorry it's so long, and thanks for reading and taking the time to respond. I'm just at my wits end here.

Apple cider vinegar will cure that if she has one....

MIL's cat did something similar a few months back. It ended up that she was so stressed because of some changes in situation that she had gone into kitty depression. She needed some anxiety medication for a few weeks and now she's back to normal  

Is the litter box covered? We have a boy that was messing all over the house including the furniture. It stopped as soon as we uncovered the box. My vet says the easiest solution is uncover your box and get another. Some cats hate sharing a potty box.

My DH had a kitty named Casper when I moved in. As soon as things started to change, Casper started peeing and pooping all over. Although the vet didn't think it was a UTI, he still got treated for one. We also did a sort of behavioral modification.

The vet told us to keep Casper in an area just big enough for his litter box and food. A cat isn't going to smurf where it eats. Luckily, we had one of those large dog crates for our dogs we had, and kept him in there for a week, and it worked.

Until we moved....

Quoting I'm His Amy He's My Rory:" Is the litter box covered? We have a boy that was messing all over the house including the furniture. ... [snip!] ... we uncovered the box. My vet says the easiest solution is uncover your box and get another. Some cats hate sharing a potty box."

They've been sharing it for a year now, and this is the first time she's been doing this.

And no, the box is not covered.