Do not limit your help with this because of love. If he wants to change things, he will! But before this happens, he needs to learn humility and admits that his use affects your couple and therefore he needs to do something for your sake and his. He is genuine when he says he will but then his head stops him because he realises he needs to reach out and this is something that addicts of any sort struggle to do because they dealt with their issues and sadness via a lonely path. So the real step for him is to admit he needs to reach out. Regarding your relationship, I would advice you to leave it to him every time he uses and not being part of that world. Put firm boundaries and follow it through: “If you decide to use, please do it in another room and do not come to see me that night.” If he trespass this demand then you leave the house to go to a friend’s or your family’s house. But that means you need to arm yourself for these situations: tell your family and friends so they are aware of how to help you. You and them should go to meetings about cocaine abuse or/and study it online. That would help everyone to deal with the consequences of what the drugs - not your bf - have lead him to behave like. Create a tight support for you as this is the only way you’ll have strength to deal with the consequences of this controlling, self-destructive and devastating drug.
Please, take care of yourself; it is YOUR life.