My mom and dad were in that position once, she said she would have to leave. He got help. I asked him why it made a difference. He said because she had never said that before. She did not threaten, it was kind truth, and even then less for her benefit as the kids, and to maintain their view of him.
She meant it, but she also totally supported him, and he her, as he her. For them, it was about something much more different than chemistry, or habit, or addiction. (Even though they retained the chemistry to the end of their lives). It took a lot of self-sacrifice, boundaries, and maturity, tbh. And faith, in God and each other.