Hey there. Im wondering about the same thing. When i was molested by my cousin at 7 yrs of age, i cried n told my mom the next day. It was touching only though.
But till this day i havent been able to tell my family about what my brother did, which was similar to ur situation. In my case, it'd crush my parents. They already have a lotta crap to deal with.
My fiance knows. Ive been having flashbacks after having repressed what happened to my childhood, for a couple of years now. I need help, but cant, cuz then id have to tell my parents.
If ur cousin may be suseptible to molest another child, or ur suspicous, definetly tell ur family. It could bring him down a lil.
The Q is: would u be comfortable knowing ur family knows about it?