porn issues

So a couple weeks ago I found out my husband has a flicker account and has like 100 something friends on there and has liked and joined sex groups I'm discusted I never imagined he would be into the stuff I saw. There was anal sex pussys and tits just all the pictures he liked on there and was watching really hurt. How can he watch all that and not feel bad like he's betraying me. Well comes to find out he's has this account since 2008 and we meet 2010 we got married 2012. what I don't understand is why? Why does he feel the need to be watching that stuff. He takes forever in the bathroom and reassures me he's in there bcs he has a sensitive stomach. Before I found this account. He had always reassured me that he didn't watch any kind of porn bcs he didn't see the point in it. I feel betrayed, I honestly do. Bcs  if he loves me why does he feel the need to see other pussys ass and tits it makes me feel insecure about myself maybe I'm not attractive to him and he feels he needs to watch and fantasies about other women to get off. I don't get. Well I confronted him about and to my surprise he tried to deny it when I saw it with my own eyes didn't apologize or felt bad about it. He was the one acting mad bcs he said I was acting crazy. I just don't know why he would jeopardize our relationship for minutes of pleasure. After he knew I wasn't ok with it. Makes me think he's capable of cheating if he's fantasizeing about other women. Well turns out he's had it our whole marriage before we were even married and who knows what else he's been hiding. I knew something was up since he would take almost 2 hours in the bathroom and he would always say he was tired and never wanted sex. I had that feeling. But never thought he would be that kind of man. I'm disappointed and hurt. After that big fight we had the next day it was my birthday and I told him I was leaving to my moms since he didn't want to give me an explanation about why he feels the need to be looking at that when he's a married man and a dad. He didn't apologize or even wished me a happy birthday. He said if I wasn't happy to go then. And of course my mom convinced me to come back home but we haven't really talked about it since.  And I'm just wondering what goes threw a man mind to have these thoughts or needs and desires when there married and there wife is whiling to have sex when ever. I don't understand! can Someone tell me what there opinion is on all this. I'm certainly not ok with it for the simple fact that he hast been honest with me about certain things and is putting our marriage on the line bcs if I can't trust him then what's the point. And after this big fight he deleted it but today I saw he was searching on instagram. After I told him I wasn't ok with it and that big fight we had. he's hurting me by watching that stuff. I really don't know what to do. I feel like I don't know him, like somehow he betrayed me and I feel disgusted with him. What should I do?!