In an instant, you say, do, or write something you regret.  Why and how?  Because you are human.  You are capable of every possible slight, big and small, for you are part of a limitless Consciousness that creates.  Do not think, “Oh, I could never do that!” for that separates you from other humans, and before you know it you have done the same thing yourself.  Guilt is toxic.  Humans do toxic things.  How to clear the guilt?  Realize that you forgot who you are:  not only human, but both human and a soul.  The more you remember this, the less you do things that you would label “bad” or toxic.  But until you awaken fully, forgive yourself for lapsing and get back to the process of awakening.