It won’t be easy, but you can do it because you love him. Continuing to keep his life comfortable enough that he doesn’t need to change would be enabling his addiction, which isn’t good for him either. You can make a hard choice while also loving and caring about him. His addiction and his reaction to your boundaries is not your responsibility to manage, and doing so actually handicaps him, doesn’t support him. Separate who he his from the addiction he is struggling with. If it’s your goal to be a supportive force in his life, you can’t do that effectively if you are struggling to keep yourself okay. You matter, and he matters, love the both of you while he is too sick to.