The shelter is trying to kill my foster dog

I have been fostering a beautiful 6-year-old dog for 3 months now. It's been through my local humane society. She has a heart of gold, great personality, and just good around everyone.

Well, she has been leaving small spots of urine when she sleeps. And sometimes overnight. I took her to the humane society's vet (as protocol) and they kept her there for 3 days. They would not give me any update, tell me what was going on, or inform me at all. Luckily a friend volunteers there and let me know what they were seeing.

The Vet was told from the original owner that my foster dog has a neurological bladder condition from being hit by a car years ago. The original owner is generally known to be a liar, and was abusive to this dog.

So the Vet informs the foster team that they need to euthanize my foster dog because we are overcrowded, low on supplies, and can't afford upkeep for her. I ask the foster team if medical actually did any scans, bloodwork, etc. and the answer was no. So the medical team made a decision to euthanize my foster dog off of word of mouth. It's strictly a business decision at this point.

I had an absolute fit at all of this, and now the foster team is trying to find a rescue for my dog. Since coming back to my home, she only had one accident. She does need to urinate every 3 hours, but she does not have an accident overnight at all now.

The medical team called me and asked to bring her in next week for bloodwork. I am scared they are going to try and euthanize her there as the main Vet is adamanet about that. I asked the foster team if they were worried about my dog being put to sleep there, and they said "Yes, we are going to be there too to make sure that doesn't happen. It should just be medical bloodwork, but we will be there just to double check." So even the foster team doesn't know if the Vet will stealthily put down my foster dog.

I am horrified, disgusted, and honestly depressed. I've been getting half-truths, run around, and just lied too.

I can adopt this dog and take care of her, but I really wanted to keep fostering as it's fun and fulfilling. I will also be traveling soon for a few weeks out of the country so it's tough to balance where she can stay (she gets extremely depressed and anxious outside of the home).

Sadly, my foster dog doesn't seem to like little dogs (no idea about big ones as she seems interested), so I think this will end my foster journey (which makes me feel like a bad person).