You didn't plan to fall for him, but life doesn't let us plan things anyway. You loved his smile, the way he protected you and made you feel safe, the fun times shared doing nothing, how smart he was, the trust shared.. Oh, and you smoke meth together.
So you dated, you live together too. It was mostly great for you, but you're not one to show you're hurting, you manage it on your own. To them you are happy, not vulnerable. But he wasn't happy with settling. He cheated, twice, and you forgave him. Forgave, not forgot. Now you're unable to trust anything he says, and it hurts you like nothing else. He is clearly the one in charge with the relationship.
So no surprise things get violent. Dominance and meth don't mix well in a boyfriend. So the situation worsens, you're too hurt to get past, too in love to let go, too weighed down by views of yourself. You want to quit toking, move on in life. But why? Its all that makes you feel good inside, even if only for a short while. A million excuses as to why you can't quit, not now, one day. You're good at procrastinating, but reality won't wait.
You aren't happy. You two only have a good time when you're on it. The truth seems clear, he loves meth, not you. The pipes cant run out, because the pipe is now the only thing you two have in common. Losing meth means losing him forever, accepting he's gone.. now the high is all you have left.