The feeling of doing something that you wish you had never done. Feeling regret, you would do anything to turn back the hands of time... Or die to get away...
You can vent anger, control lust, own up for guilt, but you just cannot undo what you've been regretting.
Regret is that full time shadow with no limitation of day, light, time, or person. Other than those who just choose to forget, of course, but you can't forget when it's screaming at you in the face every time you feel a smile or a laugh rumbling up your throat. Regret can make you wan to tear your hair out and slice your arteries into slivers of defunct tissue; it can give you self-esteem issues and take away concentration; it can ruin relationships and make you say 'FML' 24x7.
I regret being born at all. The world would have been a better place and all those poor starving babies in third world African countries could have consumed the food that's been wasted on me all my life.
Little homeless orphans around the globe could have had my loving parents, poor things.
The money spent on my education could have been utilized on the education of those children in developing nations who work as child labourers 18 hours a day.
I regret not being able to do anything about the fact that I was born in the first place.
I regret being born.
To argue which is worse is an exercise in futility; for the weight of their pain is subjective: the falling out of a friendship because of an unbridled tongue, the loss of the one you love because you didn't speak up, someone committing suicide because of something you'd said. The pain is there, festering; gnawing at your soul; relentlessly reminding you of its reason for existing: yourself. There's no one else you can blame; for there is no one else TO blame. All you can do is bear this burden, because it is a burden you've forced yourself to bear. And you do so willingly- subconsciously seeing it as penance for your sins.
Regret cannot be satisfied with distance- that is the moral of this story.