Maybe you raised such a loving son that he can embrace you both....
and then too maybe he knows you love him but he is trying to win his dad's love by choosing him over you....which would mean he doesn't know his dad loves him.. how sad is that?
It sounds to me like you did a wonderful job of raising your son despite difficult circumstances.Be proud.

I know its painful and scary to be with the one who violated and hurt you so badly.. but I hear strength in your words.... you have already risen above your abuser...

Be strong.. if you decide to go...Good Luck....Faith