Greetings @jada1! 
You bring up a good discussion here- yes, hexes and curses are a very controversial topic in the witchy community!
While the Wiccan Rede is specific to Wicca (although witches of various followings may use it as guideline or have similar codes of ethics), it is essential in any branch or type of spellwork that you follow your own ethics.
When a situation arises that makes you consider casting hexing or other forms of negative energy, it opens a good opportunity to take the time to examine your beliefs. Take a deep look at how you feel about the idea of karma and/or the Threefold Law/ Rule of Three.
Before moving forward with negative magick, you should ask yourself:
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Am I doing this in the heat of the moment? Casting in an emotionally charged state has numerous outcomes that should be considered.
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Is this something that could possibly backfire on me? You should never cast something that might backfire, hurting yourself and/or your loved ones by accident.
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Could this spell manifest in something much bigger than I want? It is easy for even simple money spells to take a direction different than what you had in mind- so be extremely careful with casting dangerous magick.
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Would the deities I work with approve of this? If you work with deities who preach love and white magick, you may lose standing or even your connection with a deity who frowns on casting black magick.
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Is this something I will regret later? Once cast, the spell and its energy is out in the world. Never cast spells you feel you may regret or that might come back to haunt your practice.
As for your specific situation, it does sound like a very complex scenario. It’s natural to look for magick to solve problems- especially ones as powerful and upsetting as this!
Although I don’t know the details of your situation, if there is an adult harassing you (especially as a minor) please consider seeking legal help. Like you mentioned, many sites have cyber-safety rules in place that can help protect you. I think this is a great idea to pursue! 
When you have taken steps to protect yourself as best you can, I think then it will be a good time to turn to magick. In addition to general Protection Spells, there is one spell in particular that I recommend for cutting ties and seeking freedom from bad influences:
Wishing you the best of luck, Jada! Stay safe and blessed be 