In your opinion, do you believe a er spaniel could live in the backyard?

I have a er spaniel that is almost a year old, and ever since my parents bought him for the family, he's had to live outside (that was the only way my mom would give in to a dog). He has a corner fenced in the garage with a doggy door leading to the backyard and he has his food, water, and bed in there (since we live in texas and it gets really hot in the summer he also has a water bowl outside that is changed daily). As a puppy, everyone spent time with him and he was allowed to "visit" with us. But as he got older, everyone lost interest in him and I became the only one caring for him and training him (sort of like a single mom, if you wish). My brother wanted the dog very badly but stopped coming outside to play with him and doesn't even care for him. He won't come on walks with Chris and I, and his idea of quality time with him is to go outside and talk in a squeaky voice, pet him, and then leave for his friend's house. Since we got him for Christmas, I spent my whole Christmas vacation playing outside with him, and making sure he was okay. When I started school again I would do my homework outside on the patio (regardless of the weather, although my parents would yell at me sometimes to come inside). He is no longer allowed inside at all, because he chases our cats and my parents say that he will start running in the house every time the back door is opened if we let him in. He also isn't potty trained because he doesn't live indoors (although he knows not to pee or poop on the patio). He was such a good dog, and then all of a sudden he became a problem. I'm not sure exactly when it began, but I do think that the causes are that he doesn't get enough human attention, and I'm sure you all will agree with me when you hear his behaviors. He has begun chewing (although he's never had this problem before), and he actually began while we were away on vacation for three weeks (the neighbors were watching him). He chewed up our doormat and so we got another one. He chewed that and is still chewing on it occasionally. The other day he chewed the fabric off of our little trampoline, which he's never tried before. In my opinion, he's bored and lonely. He's seperated from his family. Some other things that he does: he jumps on the patio furniture and table (he only jumps on the table when he wants to see inside the house. It's the saddest thing ever, he sits on the table and just stares at you through the window, it makes me want to cry), he jumps on people when they first come, he pees sometimes out of excitement, he does not listen all the time, he does not come or stay all the time. I realize some of these are my fault and I trained him very wrong, but this was my first time and in all fairness I had very little guidance from my dad (who has had dogs) or help at all. I wish he could at least come inside when we're home, just to sit there while I'm doing homework or watching tv or something, but my parents won't allow it and it makes me so sad that he's alone for such a huge part of the day and I love him so much but no one wants to help, and my parents were going to hit him with a stick everytime he did something bad, and now since it's not working they want to use a shock collar and I am so upset and I don't know what to do. also, he runs out the gate sometimes when it's open and I'm so scared that he is going to get run over because he doesn't come back, even if i call him and dont chase after him. also, he has cherry eye and my parents dont want to spend the money on the surgery, and now they won't even get more drops for his eyes so they're not so goopy. they don't see him as part of the family, they see him as just a dog that doesn't need as much attention when something has gone wrong or he has a problem, and they expect me to solve it by myself, but I can't, and I don't know how and I don't know what to do. I want to spend time with him but I've started high school now and I don't know how I'm going to balance caring for him and getting all my work done. Also, I don't want to get rid of him, this is my first dog and I want to make things work. Besides it would be traumatizing to him. I just don't know what to do and I wish he could come inside, it's not fair to him to watch his family on the other side and want to be with them, but they won't let him. It's not fair.