Sorry it's long but I think the background is probably relevant?
I had 3 dogs, one was a rescue French bulldog.
She was treated horribly, she was brought for breeding, locked in a crate 24/7 outside and left there to eat/sleep in her own poo and wee
until she would be old enough for breeding. She developed v bad mange and ulcers in her eyes and pneumonia, bronchitis, heamatomas in her ears and has stunted growth.
Shortly before she was 1, the owner took her to the vets, her skin was just scabs and sores with no hair. He left her there for 5 weeks before calling to say he doesn't want her anymore and they should put her to sleep. I saw her and fell in love with her and was there when that conversation happened. I said I would take her, his reply to the vet telling him this was 'do what you want, let her have her. I don't care, I want nothing more to do with her'
Due to her ill health she had to spend a few more weeks at the vets before coming home with me.
She has very poor eye sight and poor hearing so would use the other two as sort of guide dogs. She loved them and they loved her.
She was constantly going to the toilet inside as she never knew anything else and it took me around a year to get her to go outside.
A few weeks ago one of my other dogs very unexpectedly passed away in the night 
she had a hard time and didn't want to leave the body.
Since then she has been worse than ever with weeing in the house. I have been taking her out as often as possible, I have even left the back door wide open for her but she will still wee in the house.
Any ideas of anything else I can do to help her?