Husband finds other women more attractive...like his cousin

My first time here.. so my husband told me he is attracted to his second cousin. he said he used to love her and that he wishes our relationship could be like how they were (Playful and fun- ya know like how cousins are) we had twin boys about 6 months ago and he told me this when I was 3 months postpartum and also said that he wasn't as attracted to me as he is to her. He did have her on Facebook and would look at her pictures and then pleasure himself in the bathroom to the pictures, and he even told me he thinks about her when we are making love. Before we were together, he did try to date her, but she denied him. It's been 3 months since he has told me and since then I have had difficulty being intimate with him and honestly just full of rage a lot because of it. How am I supposed to get over it like he wishes I did and that I could just use what he said as a way to build our trust and help each other with each other's desires. He also recently told me that he has difficulty lusting for me like he does for other women.