OK, you reacted in a very negative way to him watching porn and he is trying to duck now and you are saying he is a liar and dumping a lot of other loaded language into the situation because he is evading your inquisition about it. The situation should never have gotten to this pass. It does not have to be this fraught.
A lot of women don't care one way or the other if their guy watches porn. They are simply indifferent. It does not push their buttons, it does not bother their body image or self esteem, it doesn't trigger jealousy, they don't make artistic judgement of the crappy filmmaking, their feminist principles are not offended, they don't think their guy is cheating. They just don't give a hoot. They would not demand their partner give them an accounting of his porn viewing, it wouldn't occur to them that it mattered at all.
So the question is, since the above profile is obviously not you, what does porn signify that distresses you so much? Is this about control? (It kind of sounds like it.) Are you working with a counselor to see how to get to a point where he can live his life in this little way (or other little ways) without you grilling him and getting all emotional?
Of course he is lying, he thinks you will be hurt, and knows you will be mad, or merely thinks you are reeling out a lot of rope for him to hang himself with. I would probably wonder what the upside of being truthful was in such a situation myself.
I think you should look at why your reaction was so violent and work on that. Work with a counselor on whatever the base issue is for you. If necessary, as Tink says, postpone the wedding. It doesn't sound like this fight is only about the porn.
You have expressed to Him Your "devastation and betrayal in a very negative way" - I'm certain You have also expressed to Him that You are "perplexed and hurt" - and regardless of all that, He continues to use porn and lie to You. SO - He knows You don't want Him to look AND You know He looks anyway - it's really that simple. What You see is what You get. If something in any relationship is bothersome to You in the beginning it will only magnify with time. I don't mean His watching will necessarily magnify but if it continues at any level, Your DISMAY of Him watching it certainly will. There is nothing You can do or say to keep Him from looking at porn if He chooses to do so. He doesn't want to stop looking at it and He lies to You because He knows You disapprove. This situation is not going to improve if one of You doesn't change - He must stop looking - OR - You must stop objecting - You cannot have it both ways and have a successful marriage. Might be a good idea to put the wedding off beyond November and see which of You are willing to make the change. Good Luck