That is beyond unspeakable. I'm very sorry to hear about your cousin, or that you even had someone like "Joe" in your life & family. I hope things wll get better for her.
I was thinking, the other day, of my 8th grade English class. It would have been 1970. The girl who sat in front of me was very pretty, & often mentioned, in passing that her boyfriend was 19. So, a rapist. Only at that time we didn't think of things that way. Age of consent laws were regarded as obsolete & patriarchal. A lot of high & junior high girls had boyfriends in college or beyond. At that age we didn't have the perspective to wonder what does a guy nearly 20 have in common with a 14 year old girl?
How things change. Yet even so, the law declined to help your cousin or put a end to Joe-the-rapist. Someteimes you have to wonder, what's the use?