How Responsible Am I?

"Then the Lord said to Cain, 'Where is Abel your brother?'  And he said, 'I do not know.  Am I my brother's keeper?'"  Genesis 4:9 (NAS)
God didn't answer yes or no.  But He did say, "What have you done?"
You own your thoughts, attitudes, words, and actions.  You also own the consequences of those things.  And you're responsible for the consequences your words and actions have on others.
Others, in turn, are responsible for their own behaviors, as well as the consequences to themselves and to others.
Take responsibility for yourself, and while you're at it, hold others answerable for themselves.  That's not being judgy.  That's being responsible.
"So then, each of us will give an account of ourselves to God."  Romans 14:12 (NIV)