By your heading ‘I deserve better’ It speaks volumes, you know why? Because for you to say that you’ve already realised that you need to leave because you want to be happy and reading your story you don’t sound happy. You’ve tried being a support for years and have stuck out each relapse but the trust has gone and its hard to keep a relationship going without the trust. If it helps, maybe leave and say you are leaving but will still be around to support her when she needs. You never know, it maybe what she needs to stick to quitting as soon as shes on her own then you can slowly rebuild the trust