Am I wrong?

I am 44 years old divorced with 3 adult children 2 new grandbabies. I live next door to my parents. I have a brother and sister. My parents are age Mom is 78 Dad is 72 I am the only one who takes care of them out of the family. My Mother has a few health conditions. My father is a veteran. They receive around 6,000 a month together between VA and Social security. My father has congestive heart failure along with diabetes and lots of other health conditions. Luckily we both own our homes and don't pay a mortgage. I take them to every doctor appointment. I have to fight with my Dad everyday to wear his oxygen which he should have every day. I have to remind him every day about his insulin, he does have a nurse that comes out 3 times a week but all she does is his vitals. He lies to her all the time about not eating sweets and other food that is bad for him. He was told not to drink cokes he has kidney failure. But he still continues to drink them. This is an everyday battle. He gets mad at me when I tell him, he says he is not a child and knows what to do. I have sacerficed my life to take care of them. My Mother has asked me not to work to help with him she says she cannot do it alone. However I have no income I have always worked but when I did I always had to leave my job to come home and take care of them because he would have low blood sugar or way to high. I'm paid 60.00 a week to clean only 6 hours a week by home healthcare but I do way more then 6 hours.My mother is so mean to everyone. She's negative and always mad. When I drive them my Dad always is telling me from the back seat slow down, put your blinker on etc. I can't do anything right. My brother and sister never come to help. I come home and cry and just feel like I'm tired of all of it but they are my parents so I begin to feel guikty. I have major back problems and always have to take Dad's Walker in and out of the car when it's a grocery shopping I do all the loading and unloading alone. This is so hard especially the fighting everyday. Just this morning Dad went to get donuts and is not even suppose to be driving but left without me knowing. My Mon didn't say anything she let him go. He will listen to her but she refused to tell him anything. I told him please don't eat that donut he said why I'm fine. My sugar is good I did my insulin He thinks because he does insulin he can eat anything he want. Am I wrong for feeling this way? I also feel that if she doesn't want me to work because I feel that she wants me to always be the bad guy telling him what he can and cannot do that they can afford to pay me something out of their pocket for all I do I have to live and I cannot on 60.00 a week. What to do? I never can go anywhere I don't have a life! I rarely get to see my grandbabies because Mom will critize anyone and everything. It's so embarrassing when we go out in public she stares at people all the time. Saying things like look at her OMG or look at him. I have recently caught myself acting like her. Being mean and negative with my own children I don't want to become her. My kids have even noticed telling me Mom what's wrong? It's just that I want a life of my own but feel so guilty. What to do?????