You can't love someone to health, no matter how hard you try. Love does NOT conquer all.
He didn't leave because "you weren't as loving as you should have been." He left because you get in the way of his addiction. That's all that matters to him now.
You feeling guilty is like pouring a tea cup in the ocean...it didn't matter then, it doesn't matter now.
Please focus on yourself and finding your way to a better life.