Does anyone else do more than their share yet gets criticized more than others who do nothing?

Our parents started declining a few years ago. Eventually, both needed someone with them around the clock. My two sisters live nearby and take turns being there, working around their schedules. Both sisters developed their own health problems during the same time our parents did. Both are amazing care givers. I started going more often once our parents needed someone in the house at all times. A paid care giver comes to the house in the day during the week. Thank goodness our parents have a decent pension to cover that. Adding up the days I've been there, I have been there a third of each year for the past three years. I took a job that pays minimum wage but allows me the flexibility of being there to share the care giving duties. I turned down better jobs to be available for care giving respite. I became too available. I did this to be there for our parents and for my two sisters so that they could do things other than work and care give and to protect their health. My being there allowed them to go on vacations, go to one sister's son's college graduation week out of state, spend time with their own families, work overtime, rest, etc. When there, I work my bottom off and thought that was appreciated. I even do a lot from a long distance. We eventually got cameras to watch for falls and potential crooks. I have overheard on those cameras several conversations that were so hurtful. I've been accused of being dramatic. They also say the two of them are doing the care giving alone, as if my contribution is not much. When I did voice, in anger, that our one brother, who lives two hours closer to our parents than I do, does nothing, I am now considered the bad guy. Instead of giving me the benefit of the doubt and realizing that outburst was uncharacteristic, I got criticized. Why does the one who shows up one quarter of the year get criticism while the one who does nothing gets praised for showing up for an hour about twice a year? Of the four children, I am the only one who has never taken from my parents. Our mother provided child care for both sisters while they worked. Our parents bailed out all three of my siblings and many adult grand children financially throughout all of their own bad financial decisions, never questioning their priorities. I have always accepted the consequences of my own financial bad decisions, quickly ending those behaviors early in life, and refused to take advantage of my parents that way. My husband thinks I'm the only one who owes them nothing. I might sound like a martyr in this post, but I don't act that way when I'm there. I'm not asking for praise, thank-yous, or money. But I could do without the criticism. I feel like no good deed goes unpunished. It makes me want to stop helping and seek a better job for myself, hence a better future. I love my parents and want to be there for and see them. My husband and own two adult children have suffered through my long absences, less income, miles on our cars, no family vacations for three years, and me being stressed, angry, and exhausted all of the time. Putting my family at risk financially will land us in our own possible desperate care giving situation some day in our own old ages. I will not let our two children be our care givers. While it's an honor at times, it's physically and emotionally exhausting. It is the most stressful thing I have ever done. It makes me think and say things out of character. Care giving is more bathroom related than anyone talks about. Medication situations, constant appointments, advocating for parents whose generations trust doctors even when they don't have their patients' best interests at heart, blood sugar checks, insulin injections, running another household, vet care for their pets, and so on. Lifetime TV movies would have you believing it is about spoon feeding a sweet old mother or father and remembering the good times. I don't know if I'm venting or hoping for advice. Thank you for any kindness or advice.