"My grandmother diagnosed with lung cancer," Loyola significant influence

The Question is: Indicate a person who has had a significant influence on you and describe that influence.
I would appreciate any help! Thanks

One experience that has impacted me the most was the passing of my grandmother. My grandmother was diagnosed with lung cancer but never smoked cigarettes in her life. It was the hardest thing I have ever gone through; to see someone so loving and caring go through such torture and there is nothing you can do to help her made the situation even worse. This is highly significant to me because I lived with her my whole life and she taught me so much about life.

My grandmother always told me that by working hard at everything you do and working hard in school will produce success. I believe that this saying should be the motto for everyone's life because these are vital guidelines for becoming everything a person can be. Next to my mother and father, my Grandmother was one of the biggest influences in my life. "You never know what you have until it's gone" is one the quotes that I keep close to me, this quote helps me remember the most memorable times I experienced throughout my life with my grandmother.

After the passing of my grandmother, it was very tough to not shed a tear while thinking about her; she meant so much to me. It was extremely tough to think about how I grew up with her and that she will no longer be able to see me graduate from high school and college and she will not get to see me get married. Coping with this experience has definitely made me into a more mature person. I value everything in my life and most importantly I value family. Family is the center of how I live my life and it has helped me become a perseverant individual. Most of all it has shown me how to be a loving and caring person to everyone and value the ones I love most in my life.

To say "one experience" implies "one of several." But when you say "most," it is superlative.. so there is only one.. So you should write, "The experience that..."

Let's make it so that the stuff on each side of the semi-colon could be a complete sentence:
It was the hardest thing I have ever gone through; seeing someone so loving and caring go through such torture, the fact that and there is I could do you nothing to help her made the situation even worse.

This is highly significant to me because I lived with her my whole life and she taught me so much about life.---- This sentence is too vague. At the end of the first paragraph, give a sentence that contains the message of the whole essay.

:-)