You aren't overreacting for one. But i will defend him on one aspect possibly. It very well could have absoluetely nothing to do with you. Porn sucks you in. It's consuming and if he was a habitual watcher of it before you it had like drugs and alcohol. It's hard to stop. But i agree with you that if he truly wants help and wants to quit he isn't trying very hard if your finding phones and stashes of porn. If he truly wants to quit he needs to explore the reasoning for the addiction. Me personally, i found that i gravitated towards it when i was anxious or depressed.i have self worth issues that led me to feel i wasn't doing enough to provide for my family. I was so oblivious to anything other then my mind telling me i was worthless. So i got the release from porn. That short lived euphoria and once it was over i felt right back to worthless and go right back to it. It was a vicious cycle. But i think we all have triggers and he needs to identify what those are and be transparent with you on them. Luckily after years of fighting i came clean to my wife but not before it hit massive troubles. I have her support and she keeps me accountable but its a long road ahead. I really hope you guys figure it out but if he isn't willing to change or fight to save what you have, you shouldn't have to feel the way you do. You guys have a partnership. Maybe he doesn't see the problem but that's how the addicts mind works in my opinion. He needs to see the strain it's causing as well

You could try reminding him that excessive porn watchers are mugs. They are being caught and duped by the porn industry. I enjoy a bit of excitement with real women, but I feel that so much of the porn on the Internet is silly, nasty or false - pictures that have been re-touched for example. It is also sad to see women with their bodies disfigured by plastic surgery to enhance their boobs or bums or even worse, men who have had surgery or hormone therapy to give them 'tits' to fool the punters that they are transsexual.

I do hope you will be able to convince him how foolish it is to watch such rubbish when he can have a real relationship with you.

If he really wants to stop this pornography addiction I think you should encourage him to seek out a sexual addiction support group.. It sounds like he may want to stop but needs the tools to discover how to do it.

Pornography addiction is absolutely an addiction just like drugs, alcohol, gambling etc... The fact that he recognizes the need to change is a good and healthy first step. If it were my SO, I would sit down and talk about tangible ways you both can work together to ensure he really wants to change, and if so, then set up ways you can help him, beyond what it sounds like you've already tried, which kudos to you, you're a saint for all the things you've already done.
Accountability is a beautiful thing, if he would agree to go to sexual support groups, have you or someone else on standby for when he's triggered so they can help him over the temptation to stay the course of getting clean. There are resources out there in the internet community to try to beat this addiction. Just looking cursory, I found a website, www.verywellmind.com/breaking-pornography-addictions-1270612
I pray you and your SO have a breakthrough in this area, it is a powerful stronghold to rid your life of.

You sound very strong, I advise you be the best friend for him, but at a distance. Personally I would say I'm here for you with tools, take you to therapy, talk to you, hold you accountable, but I really do think the level of intimacy you guys may experience needs to be paused not so he just knows what he's missing out on, buy so he has something to fight for. And first of all, you shouldn't have to do any of this, but you do, that's beautiful. So Remember take care of yourself, if you're being taken into dark places being with him, let him know, and take a step back. Don't let this burden you by thinking if you stay as close to him you're going to change him, he has to see that there are tools, many tools, but also that there's hope, that he's not the only one and sure won't be the last.

If he wants help, there are sex addiction support groups, specially trained therapists, and lots of workbooks/reading material on the subject.