A bit of back info first.....
My husband and I have been married 6 years, together for 7.  We had a long distant relationship/marriage up until a year ago when I was finally able to move permanently from Canada to the USA.  During our years apart, we had a wonderful relationship and developed amazing communication skills.  We saw each other 3 or 4 times a year and there were never issues.  I knew from the beginning that he was bisexual and had been with both men and women his entire life and I was fully accepting of that.
Fast forward to a year ago, I moved finally and for the first couple weeks everything was great sexually then one day he was unable to achieve arousal.  At first I blamed myself or that I really just wasn't the type of woman physically that he had been attracted to in the past. When I tried everything possible with no success we thought maybe something medical was wrong.  One day about a month ago during a road trip we decided to share videos of what excites us or what we would like once we got home.  Surprisingly, he was able to achieve, maintain and finish that night.  To my dismay it was only the sight and desire of other men that arouses him.  I brought to his attention that I have come to the realization that outside the bedroom he is 100% a heterosexual man but in the bedroom he is 100% a gay man. I thought that I could be okay with that fact but as the weeks have progressed I am realizing that it is something I don't know how to process. He has resorted to watching gay porn in order to gain arousal without me knowing in order to attempt to engage in sexual activity with me, obviously I know this is what he is doing.  The downfall is that the moment he touches me, that arousal goes away.
Outside the bedroom he is super attentive, loving and physical.  I just don't know how to even start processing.