Help! I think my husband might be gay!

He doesn't have much interest in me sexually. Where other guys seem to be very interested! 
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​And I know he masturbates a lot! So I checked out his history on his computer. His most frequent link was a guy that looked like a girl ( to clarify, has a penis and breasts but the face and hair looked like a girl). On the website the guy/girl was masturbating and using large toys for anal.
​I've found his links before and I know he has an anal fixation. I have comforted him about it in the past, but he claims there is no issue. He just likes anal stimulation. I tried to get involved but he doesn't want me to. 
​I don't know what to do! HELP!