Curses are indeed powerful, but think about what the bully has done. If it's something horrible, and has been torturing your thoughts for months, then I suggest actually taking negative energy through yourself and manipulate it to what curse you will cast. But magic isn't just one thing, it's purely energy. Find a way to teach a lesson to the bully and take action. Magic's best friends are energy and actions. Remember curses are not to be taken lightly. Not even small ones. Karma can hit you back just before you know it. I warned you.
You are going to have to do it at before dawn or dusk. At the very beginning before darkness or day takes over. Get 2 candles, hot pepper (Habanero chili, Scott Bonnet or of the same heat), clay, salt, pen, paper bag and clear about an hour of your day. You have to face the setting or rising sun.
The color of the ink, clay, and candle all must match your intention. I suggest white, blue or maybe red. White and blue both basically bring about luck and protection. However, if malice is you choice then red is your best bet. Whatever you choose they must all be the same color. Make a ring of salt put the bag in the middle. The candles must be place close to the ring no more than a foot apart facing the same direction of the setting/rising sun.
Just before you start the next step you must clearly keep you intentions in mind. Light the candles. Say out loud your intentions and eat the entire pepper. Begin molding your clay into small person while keeping your intentions in mind. Do not leave the spot, you must mold it so it is one sold peace, do not break and put it together. Put the mold into a brown bag. Out the candles with your fingers do not blow it out. Write the name of the person on the bag then find a place corresponding to your intentions. You want peace, near a church. You want him/her to leave you alone somewhere far away in nature.