Need advice with an hex

Hello fellow sisters, I need some advice in casting an hex. In short, by not getting into much details because the post would be too long, there is this person that is tormenting and harassing me and my family for over 20 years, my parents tried everything from reasoning, to legal ways, by calling the police but this person somehow always get away with it. I've reached a point where I'm at my limit and on top on everything after a lot of reasoning I've decided that I should try with an hex. I'm relatively new to the world of witchcraft and I needed some advice to cast an hex, I've informed myself a little bit and I think a jar spell would be what I'm looking for, so if you could give me some advice on how to procede with it. I've also read about protecting myself before the hexing and cleansing my space after it, some people wrote that it is good to procede with out and other say it's not necessary so I also needed some advice with protection for me before and after casting the hex.

Thank you in advance.