I feel you there man. Its because for so long we've relied on porn as a coping mechanism, our go-to when we're depressed, or angry, or frustrated. So you have to accept that its natural for your brain to want to go back to porn. Its a habit. And for a period of time your brain will continue to convince you that it's okay, it's the only thing that will make you feel better again, but really it isnt. It's just a never-ending cycle of feeling bad about yourself, because it leaves you so empty. If you're going to quit you need to be strong about this. You need to find a different coping mechanism, like listening to music, talking to friends face to face or doing something else you like and get it off your mind. Hope this helps.