My SO is mad at me because I caught him watching porn.

My man was at work and he borrowed my phone because he broke his. So in order to try to contact him I went on our tablet and I was going to download fb messenger to send him a message. As soon as I turn it on the web comes up and I see pornhub. Specifically a babysitter video and it was under "most visited". So I freaked out. I don't really have a problem with him jerking off to porn BUT the reason why I am angry is because neither of us takes the tablet out of the house. Which means he was doing this while I was home. Either while I was sleeping or while he was in the bathroom "taking a siht". He has told me he jerks off when he is on break at work because I'm not around and he gets horny, and that I'm ok with but he knows when we are home together i always want to have sex. So I'm angry because we havent had sex in a few weeks and now I know he would rather jerk off. I confronted him about it and he lied right to my face even though I showed him the damn video and now He has the nerve to be mad at ME! What do I do? How do I get him to understand that I'm mad that he would rather watch porn then have sex with me? He always said he would never lie to me...