Spend the night when she is not there or sleeping, take a shower and wrap yourself I a towel and walk over to him and grab his cock with your hand while dropping the towel with your other and and whisper to him “I've wanted you inside me since I was 16, now I'm going to suck you off and if you like that you can have the rest of meâ€
Trust me as your wet and. Asked stroking him he will cave and you find out if it is worth the family knowing or not.
Just talk to him when he is alone and tell him what you saw and that you want it.He can't prove you tried to seduce you without a witness( if he is straight laced) and ask him where to meet for the action if he is interested.No one will know as people are busy with their lives.Your cousin--is she working,pregnant,busy with kids,out for shopping while he is with you?