I sympathize with your position. No one deserves to have to pull all the emotional weight in a relationship.
You say you are well matched, but it doesn’t sound that way to me after i read your story. Being sad for days after a fight, crying all the time… Is that how you want to live? You are feeling resentful and I don’t blame you. You keep trying and trying and he keeps falling off the wagon, so to speak.
A thousand times this:
< Ask yourself, if your boyfriend isn’t actually capable of changing, would you stay?>
Can you endure another 5 or 10 or 20 years of your current state? Could you endure a few good months followed by a backslide, Wash rinse repeat, maybe forever? Do you want a relationship built on your emotional endurance?
You say he is very loving when he’s not losing it, but this:
<he tells me that he is sorry to hear, and that my feelings are in my control, not his.>
does not sound compassionate or loving. It sounds small. Considering his behavior is causing your feelings of sadness it’s also wrong. It also sounds as if he is not recognizing the role he plays in your emotional upset.
If you were my sister, I’d encourage you to strongly consider not making the second move to live together in a more permanent situation. Your instincts about this are valid and you need to listen to them. That kind of move with a boyfriend should make you happy, NOT scared. It will be hard to let this relationship go because of all the wonderful parts, and it will make you sad. You will cry. But you are already sad and crying with no end in sight. As difficult as it is, as vested in this relationship as you are, I think you should let this one go. 🙁