Writing a letter?

I was abused as a child by a man who was my dad's friend, I have recently been to the police to report this crime and it's turns out there is nothing they can do about it because it was already investigated 25 yrs ago. I am finding this hard to come to terms with and have been advised that I might write this man a letter explaining how he has affected my life, just as a way for me to get some closure. What I want to do is write to his wife and explain to her what he did to me and warn her about the man who she is letting share a home with her two young daughters! I am keen to do this but am worried what the reprocautions would be if i did? I already made contact with him about 4 months ago when I told him I would be going to the police, to tell them that he had abused me when I was 3 yrs old, I pretended to be someone else on face book, when I confirmed it was him I told him that I remember that he abused me when I was three and that I was going to the police . He closed all his face book account but not before I could find out were he lives, phone number, address etc.. I would be so greatfull to receive some advice about this. Thankyou