I totally agree with @backseatcookers
OP, you don't even seem to understand what you are doing. You are swinging between extremes and seem obsessed with getting inside his head. My daughter has EUPD and I know how hard it is. But you need to engage and take the drugs. Take some mood stabilisers, even for just a few weeks. I promise they will help to calm your mind.
You really need to unpick your self esteem and self worth from being wrapped around and dependent on your partner and also your sexuality/desirability. Your happiness seems 100% to rely on him following the rules, sadly human nature means that we all make mistakes and IF your oh has looked at porn, he has aplogoised and moved on. You are not less desirable than the women in it, watching porn does not negate your attractivness to your partner. He is allowed to look and if you can not deal with that , if that breaches your rules, then you need to end the relationship. Imagine telling him he can only eat a roast dinner for the rest of his life and isnt even allowed to look at pizza or chinese food. He hasnt eaten pizza or chinese, but he las LOOKED at it. Not eaten it. And looking at pizza and chinese does not mean he does not like roast dinner anymore.
You also need to be honest with yourself, In one part you say you were hounding him over the emails and porn etc. But then you say that nobody knows how much you obsess and you pain a smile on etc. I do not believe that he has fallen for that for a second. I have seen this in my daughter. She believes something totally different to the reality. WHat happens in her head is very often nothing like real life, that is just the thought patterns and obsessiveness warping her reality.
Please please take the medication they give you. So what if you gain a little weight. You should be fat and stable over skinny, obsessive and neurotic. You could potentially lose your relationship if you do not take steps to get yourself back on track. The best way to do that is to listen to the DOCTORS. Engage with the treatment.