You must not fight with only spells but with the heart,mind and will.Try to resolve the problem without harm.And remember that patience is a virtue,think about the root of the problem,and think about it.Hope it helped you.
If your so determined to not to do things the right way I can I can assure the beating from this ex criminal will come and by the frantic nature of your messages your not much of a fighter ,and by your immediate dis missal of everyone's spell help you don't totally understand magic and and how it works so no spell is gonna work for you. Your best bet is standard bully teqniques befriend someone bigger and baddwr than him or group attack many people making a scene over him will attract attention to him and keep him backed down until you can come to a much more intelligent solution
Sorry your in this situation but if you ever wish to practice magic I would suggest learning how it works and get a much calmer mind on things to be able to think things through
ToxicDragon9 is right,you must not be scared in saying your problems onto someone you can rely on,its not true that you are coward in saying the truth,it is worst when the time goes that your enemy hurt you and your parents will be worried but didn't know why this happened,..
Why you relies on spells if there was marcial arts?Try also to learn taekwondo even basics helps.But the best way to eliminate bullies is to ask teachers,school counselors and your parents.Its the best way to do.
In my study in magick I've learned that such spells, harmful spells and even revenge spells, are associated with dark energies therefore black magick. There is only a specific type of situation that can allow you to cast black magick and not have any kind of dark energy come back to you: it is when you have tried everything which intent is to try and be the bigger person, trying to make peace, etc and that you know that it is never going to work and the emotion, the energy, the sentiment and power in you is so strong in hateful energies and is as thick as stone, completely honest and true. I see in your situation fear is what drives you. I suggest a luck spell acctually. I use protection spells when I deal with things I do not see such as energies and spirits but if you prefer a protection spell well that should be just fine. just do not expect a materialized body gard around you.
You seem young and maybe a little uneducated about magick and its properties. Maybe study more and all the advice that has been given to you on this forum is relevant. Talk to your parents and any other adults around you, magick is not the whole key to everything. Think smart.
Blessed Be.
Then talk to parents. Although this site is designed to learn about magick, it cannot solve every issue in life, regardless magick is not an instantanious result, you have to work alongside it.
Therefore even if you cast a spell, you would have to put some manual work into helping yourself.