I acted in a simlar way in my marriage, but without the porn. If you think it is right and justified then go ahead. Just realize the pain that it will put him through. I realize that he has pained you but somebody has to break the cycle of "you hurt me, I'm going to hurt you back"
Have you thought about getting a sex toy to please yourself? Or try the seperation. Tell him your needs are not being met by him. If he wont listen then tell him how serious it is. I wish my wife would have done the same, because I told her I thought about cheating a couple times but didnt.

Best of luck