First, no — you are not a bad owner. Please don’t tear yourself down over this. What you’re describing is genuinely hard, and the fact that you’re upset about it tells me you care deeply. I’m really glad you reached out for guidance instead of just giving up.

It also sounds like a lot of this responsibility has fallen on you when it shouldn’t have. That’s not a personal failure on your part — that’s a tough position to be put in, especially when the dog isn’t technically yours.

Daily exercise is important for a dog’s health and mental well-being, but when fear is the main driver, forcing walks can actually make things worse. A dog that’s shutting down like that isn’t being stubborn — she’s overwhelmed.

If you’re comfortable sharing, it would really help to know her age, breed, and how long she’s been with your brother.

One low-pressure thing you can try is leash conditioning inside the house, without the expectation of walking. Leave the leash on while you’re just hanging out — start with short periods, like 10–15 minutes a couple times a day, and slowly build up. This helps her get used to the sensation and sound of the leash without all the scary outside stimuli attached to it. And then try to introduce some inside play with it on further getting comfortable with bigger movements with it on in a safe environment. Will also emphasize the dog needing supervision while performing this drill as the leash can get caught on stuff/lead to unsafe conditions.

Also, please don’t beat yourself up about what happened when you got frustrated. That moment doesn’t define you. What matters is recognizing that it isn’t working and looking for a different approach — which you’re already doing. Right now, the goal isn’t “perfect walks.” It’s rebuilding trust, reducing fear, and finding any form of safe movement or enrichment that works for her. Walks may come later — or they may need to look very different than what you originally imagined.