Crossing the line

When does one cross the line? 

'You've crossed the line' we're told...where is that line?

The ever existentialist Joey from Friends said it well: 'Over the line? You... you.. you're so far past the line that you can't even see the line! The line is a dot to you!'

More often than not, we know we've crossed the line when someone else tells us. So, isn't such state entirely dependent on the other person's viewpoint?

Which brings us to judging and opinion. 

Every time I 'cross the line', it is a judgement you make based on your opinion. And while it is important, it is still your opinion. Nothing more, nothing less. As such, I will keep the right to react to it the way I want. Cause every time you judge me based on your opinion, I can only get hurt if I let it do so. My role is to make sure that I don't let you affect my life because you've made a call based on your experience and interpretation. 

Of this, I have to be aware all the time because I could do the same to you.