Flirting comes naturally for those that have it within them, but there are boundries as to how far you can go.. "Suggestive flirting" is not cheating, it's being dis-respectful to your partner.
Does he dis-respect you in other ways? Put you down?
Do you give 100% to your marriage, or just live in the house, and be a housewife... It takes two to keep a marriage / relationship - sparked.
Porn is a different story. Here you probably feel that he is cheating as he is looking at another woman naked, to say the least and probably makes you feel less of a woman.. You either agree or disagree with this and if you disagree and he won't stop, then you have to make your own management choice.
Revenge is not ever the answer.
Tit for tat - either.
Sounds to me as if he has been doing all of this all of his life, you have seen it before and "tried" to get him to stop doing it, as you don't like it and now blowing up over it. So it's his nature, surely you saw those red flags when you met him, not established them later in life?