So many feelings

I think it's about to be my time of the month, because I've having overwhelming feelings for no reason, I'm debating the purpose of my life, I'm questioning everything, and missing people that are not an active part of my life anymore.

There are a lot of times that I stay silent. Times that maybe I should say something. But, I excuse myself saying that I'm not out to change the world, and I can only control myself.  But is that right?  I live in a society now where racism and violence are not condemned by the older generation. How can this be?!
A story- A young black boy comes into the restaurant to use the restroom since the neighboring vet doesn't have a public bathroom. When he was leaving, he locked the bathroom door behind him, and swiped a fortune cookie on the way out.
The vocalized response by someone to this story was "That's when you need to take them and put a bullet between their eyes before they grow up and do anything worse!"
My jaw hit the floor.
Looking at just the minor points first- 1: how do you know he locked the bathroom door behind him on purpose? A: So what if he did, it's not that hard to unlock. B:If it was an accident, still, it's not that hard to unlock. 2: The fortune cookies are free. Anyone can have one, or as many as they want, we didn't pay for them- they were a bonus. So he took a cookie. Who cares?
And finally: HE IS A HUMAN BEING you don't just shoot them when they do something wrong! Oh my GOD.
But, did I say anything? No, I didn't. I let the person that voiced this opinion to walk away while I tried to get my chin off the floor.
Would anything I could've said made a difference? Nope, probably not. Would it have created tension and hostility in my workplace? Yep, definitely.
So, do I have an acceptable excuse for not saying anything? Sure, but on the flip side, I'm enabling horrible behavior and worldview by just letting it slide.

So, what am I doing? What am I doing with this life I have?
I don't function very well with living simply for my own enjoyment. I feel as though I'm wasting time. But, is time ever truly wasted? Each moment brings you to the next, in the grand tapestry where everything connects at the time it's supposed to.
I have no grand ambition, no one thing that I must do before I die. I live simply, ever cognoscente that life is not meant to be lived selfishly. So how am I bettering the world with my life? 
I have no answer to that question.
Every once in a while people will come out of the blue and tell me that I made a difference in their lives, and I'm always confused. I didn't do anything.
Love matters. Love makes a difference. Joy can change the world. Hope can change a life.