As I was first reading your post I was wondering why you put it in the "Wicca" forum.......but I'm assuming you're wanting to know what kind of spells you can use to ease your situation....and actually, there are lots - but....would you really want to do these things?
You could bind the person who abuses you; or you could get that person to move away etc. You could do spells to get your caregiver to make the other person move away.
You could do spells to improve your confidence so you can stick up for yourself when that person starts abusing you and put him/her in their place. They have no right to do that, in my opinion.
You say you have a primary caregiver, does that mean you're too young to go out on your own? Or perhaps does it mean that you have some kind of illness or disability that would also prevent you from moving out on your own.....(I'm not being nosy and I'm trying to not be insensitive - just trying to figure your situation out
) Either way, why does your primary caretaker allow this other person to treat you that way?