How far does this pain of losing a grandmother take?

Day by day, I missed them. I remember the way that they gave me lessons from their experiences way back in their early ages. They both, took me to this stage of thinking that life is not all about you alone, you have your parents to respect and love and siblings to guide, love, help and take care of. As an eldest daughter in the family, I was destined to love each of them not because I am part of a family but it is something that my grandparents taught me, "always love your daddy, mommy and your two siblings. Having a family is a gift and as an eldest like ours you have to love them without conditions, without favouritism and this will help you to embrace the life you'll be having ahead of you". This message, marks in me, every time, that I get upset for what they're doing this message always blows in my mind. I want to tell you a story of pain. Life becomes painful every day that you know you're lied to. I was 10 years old back then, my grandparents were still alive during those times. I am studying in a public school and my parents are both working. My sister and I were with my grandparents. There's a rumor about my dad, that he is having an affair with someone who also has family. I was very mad at that time, at a very young age I know it's painful for us to know that our parents are having a mistress. I saw my sister crying and all I can do is to be strong, because no one could help her to get rid of that pain other than me because our mom isn't around. Her care for us went through even if I am already in college but during those times, my grandfather is sick, the doctor diagnosed him with Lung cancer stage 3. It was something we felt so sad. He fought for cancer for almost 2years, we went in and out to the hospital, he has oxygen in our house because he always feels like losing oxygen from time to time especially when he is talking. You will see in his eyes the hardships of fighting cancer because he wants to see us finish college college at least before he passes away but unfortunately he won't make it. I am in my third year, when almighty father call his soul to heaven the sad part of that is, we are not on his side only nana is on his, when we ask nana she told us, amama(lolo) told her don't cry to much I am leaving, take good care of yourself, then amama passed out lying on bed and nana is crying over and over again.