Wow, I'm astounded by your strength. I must have taken everything for you to write that letter and calmly walk out, without any drama. Kudos to you for that.
As for whether or not he won't want to be with you, that is entirely outside the realm of your control, just as his addiction is. I don't know where your spiritual beliefs lie, but to be honest, it is through my experience with an alcoholic partner that I discovered my faith in a higher power. It made me realize my utter helplessness in the face of addiction and taught me how to surrender to my higher power. I know it sounds like a midnight informercial, but I truly and honestly believe that everything happens for a reason.
Your decision to leave your ABF (alcoholic boyfriend) may lead him to reach that all important bottom and find recovery *for himself*. In addition, your crisis with your relationship lead you here, to SR, where support and hope abound. I'm so glad you're here. I hope you keep posting and reading as much as you like. SR is always open
(and we don't charge an entrance fee 
)