You should feel bad for your past actions and you should spend a lifetime trying to make up for it. You didn't "abuse" the power you had been given; you abused the poor people who had the audacity to "annoy" you.
I suggest you back off spell casting for while and focus more on the spirituality of witchcraft. Get to a great place of connection with the Divine, then begin to work with spells.
You are an eclectic idiot if you CHOOSE to go back to your old ways.