I don't believe you have to take care of your parent at any cost. My father had been largely absent from my life when I was growing up. Now that he is old I've told him not to expect too much from me. He still tries to guilt me into catering towards him but I have learnt to make my boundaries firmer. My motto is: feel free to look after another person so long as it makes you feel good about it. Stop when it becomes a burden.