I was crying and humming a tune.
Why were you crying and humming at the same time?
When I think about my past and did something hurtful to others, it makes me sad and I can't help but cry.
If you feel sad you should try to make amends if you can. It is ok to try and comfort yourself when you feel sad.
I'm considering suicide.
Don't ever consider ending your life. No one goes through life without being sad and it is normal to feel sad when you have certain memories.