Torn but also fed up(venting)

So my SO and I have been pretty much living together for about a year. In this time he brought his dog over to stay too. At first the dog was a little excited because I knew he was working so much she wasn't getting much attention but now, I think I'm done with the dog and maybe even him. Give some insight......
My SO bought his dog from a breeder that was on the other side of the country. He didn't research the breed or anything. Just bought the dog because "I always wanted a G.S.". Well that was his first big mistake. Now when he first got her he tired to socialise her at the dog park but because of his lack of understanding of dogs and their behaviour, he mistook the dog running to him as a sign that she was wanting protection when it really was her just saying "look at me!! I'm playing!!". Well after the 2nd time it happened he refused to take her back to the park and just left her home. On top of that, he was busy working long hours and the dog was left home alone with no one for upwards of 12 hours. Did I mention she was also locked in one room because he rented a room and couldn't let her out because the other roommates wanted nothing to do with her?!? Yeah, then to make things worse, when he was home he would sleep pretty much all day long and walk her maybe twice. Sometimes 3 times but that was rarely. He also fed her when he would get home and water(yes she had no water all day long) but sometimes he would get home really late and super tired he would forget to feed her and she would go for 2 days without feeding. (See where this is going) Now when she came to me last year I took her to the vets because she was needing her shots. The ear full I got almost made me just let them take her right then and there. A G.S. is not suppose to weight 52lbs when it's built for at least 75 lbs but she did. She also never had her claws cut, in fact they called me to get permission to sedate her so they could cut them because she was trying to bit them. She lacked discipline which was a complete nightmare for the office staff and when I told them the situation as to why she was like that, they said that her treatment is a poor excuse. Never get a dog unless you research and are prepared for the costs and dedication for the animal. In the end I promised and filled out paperwork that she would remain with me and I would over see her care but now, I am regretting it. My SO never does anything for his OWN dog because he is working a lot!! He might walk her once and even on his days off I'm still caring for her when it's HIS dog. When I mention putting her up for adoption he gets pissed and says it's his dog and she only been with him. After hearing this for months I finally snapped and said you are the worst dog owner ever. This dog deserves a life that has structure and a purpose. She needs to run daily and get some training and if not too late, get her socialised. But what I'm dealing with is non stop telling me it's his dog and she only been with him her whole life. I'm sorry but I have seen many animals in rescues have had other owners their whole life and still get adopted and live the rest of their life with a new family. It's very possible. Am I wrong for snapping at him?! Should I just kick and her out and wipe my hands free of this?!? 
My boyfriend has left this dog with me for so long I have bonded with her. Even though she knows I feed and walk and care for her, she does not listen to me if he is home. In fact, she is so wild I have to ask him to take her out of the apartment. He doesn't really walk her at all. I can't really walk for long periods because of some health issues but if I could she would be ran 5miles and given training that she need. Every time I mention her behaviour or finding her a new home he keeps saying "it's ok" or "she my dog". I'm trying to find a way to get her trained but if I can't she can't stay with me any longer. I put my health and healing on hold to care for her and my health is suffering and so is my family. Unless any one knows of places that I can talk to around Louisiana then I have to have them both leave. I can't take this any more. 
Also, unless people are willing to over look her aggression to other dogs and to certtain people,( not sure what triggers it might be their b.o.) she is not going to be an easy adoption for a family. She would have to be an only dog because she has never interacted with another. Dogs are a pack mentality and because she was isolated for all her life she has this territorial focus. 
And I just got a notice from my apartment, because she barked at the leasing office staff and "appeared" to be aggressive, she is not allowed to stay. I'm pretty much not able to do anything anymore. Maybe him being on his own with her after a year he will realise the work she really is?!? But after what I had to work with and build up, I think that's wishful thinking. I have 3 weeks to find something for her. Any help so greatly appreciated!!!!!