This is just wow!
Unfortunately, the promises are for a brief just as you pointed out. Only a few genuinely love without those toxic traits. He tricked you to love him through pity and immediately he had his chance, he lorded the relationship over you, making you fight for the relationship alone, typical of many marriages out there that are already hooked. And to think of it as a friend you already knew? I have been a staunch advocate of friendships before relationships but alas!
Well my early, you're a strong lady and I wish you well