Thanks for writing to us.
You must be feeling that the responsibilities are just thrown at you without your consent. I can imagine what you must be going through when you are forcefully tied up in a situation which seems to have no escape. You must be a very strong woman as you are able to manage to take care of your sister's child, parents and still doing great with your career.
As you have mentioned that you did confront your sister and parents about how you feel overburden with the responsibility, however, it was of very less help. So what are the other options we can think about? One thing which you can try doing is **acceptance **, sometimes accepting the situation first is the best solution. I know it is tough for you at this moment, the more you fight against the situation which is not under your control the more you get frustrated and lose out on chances of living the life. Think about what else you can do so that you feel less burden and feel better.
Do not pressurize yourself to be the best employee, aunt or daughter, but be your best self.
Take a break for a day or 2 go on a solo trip discover yourself, be as you always wish to be and get back with an open mind. Love yourself and your family and start fresh with more acceptance because caring for a loved one will not be as difficult as caring for a stranger. I know looking after your sister's daughter is none of your responsibility or duty, however, helping someone in need is not a very bad act and that too she is your sister who seems to be helpless at the moment.