How do I get my unwilling mother to go in nursing home?

I am my 70 year old mother's caregiver. My gf and I moved in with her two years ago. Her health has declined since we moved in. She has stage 4 COPD, (still smokes 12/14 cigarettes a day), is on 2 liters of oxygen, has stage 3 kidney failure, had a colostomy 5 years ago, and was recently diagnosed with a cantaloupe size parastomal hernia, has a brain tremor ( due to alcohol abuse), is blind in left eye, is 5'3" and weighs 190lbs. She had a mild heart attack and a small stroke 2 1/2 years ago. She has dementia and alzheimers. She lays in bed mostly all day, only gets up to smoke. She uses her Pro-Air and Advair inhalers more than perscribed, ( sometimes up to 10 times a day (PRO-AIR). All she does is eats (SNACK FOODS) if I don't buy them she bitches) and when dinner is done she barely eats because she filled up with junk food. She has taken 2 showers since we moved in. Her skin is dry and flaky . She will ask for a washcloth the day before her doctor comes for his monthly visit. She lies to him, doesn't tell him all that is bothering her, so we call in advance and let him know what to check on her when he comes. She refuses any and all therapy (thats why her muscles hurt because she's not using them). I get "NO HELP AT ALL" from my siblings. My gf and I are "SO STRESSED OUT AND OVERWHELMED" we don't know what to do. She is draining us financially. while she has money up the "WAZOO!" She won't pitch in for household goods.......such as toilet paper, laundry soap, cleaning supplies..... NOT ONE PENNY! She always tells us that she doesn't have any money..... and that's B*** S***. I can't afford the legal process for guardianship and my siblings would disown me. They "DO NOT I REPEAT DO NOT" know the extent of what we go through with her. When we ask for help they have some excuse. We both feel "ABANDONED", We do not know anyone who would be willing to do what we do on a daily basis. She "ACCUSED" us of "STEALING" from her. Everyone is out to get her and rape her. We can't have friends over because "They make to much noise, our dog can't bark, because he makes to much noise. She goes to bed at 4:30 pm. HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!