Don't feel stupid. All you did was believe someone you loved. There is nothing stupid about that.
It's how they operate. Love bombing, during which they wheedle out your insecurities, as after all, you are soulmates, aren't you? Then they can use them against you when the devalue starts. Anything can tip them from love-bombing into devalue mode - something you say that was perfectly ok yesterday but annoys them today, something you do with the best of intentions, a refusal to go along with their belief that they are better than everyone else, even just buying yourself something that is better than theirs! After the devalue they get increasingly cruel, and each time is worse than the one before. They hoover you back with apologies and excuses and it all starts again, but the love bomb stage gets shorter every time, and the cruelty worse. Eventually there will be a discard - either they will leave you for someone else, cause a massive argument, or just ghost you.
It hurts, all of it. Looking back at the 'good times' hurts the most, as you realise that they weren't real. He probably meant what he said at the time, as I think they do want to be in love, and hope for a proper relationship, so you weren't being stupid to believe him. It's just that they can't have one, as they aren't wired normally, so every partner will fall short one way or another, and their version of love (which is really infatuation) turns to hate when they feel they have been let down yet again.
I'm sorry you are going through this, but I still think you should leave now - totally, completely and absolutely. Block him, delete him, freeze him out. It will be the best thing you've ever done.
x