I actually found it more useful to write a letter to myself giving ME my ultimatums. My letter read something like:
1. I will no longer accept alcoholism in my life
2. I will no longer disrespect my AH by insisting that he live his life the way I dictate
3. I will no longer try to control my AH's illness or the choices that he makes in relation to this
4. I will keep my children physically and emotionally safe
5. I will pursue what makes me, and my family (being the kids and me) happy
6. I have a concrete plan, now I will enact it
7. I will not sacrifice my children's happiness any longer
8. I will make hard decisions that I know will bring a better life in the long run, even if it means that I, and possibly the kids will feel pain in the short term
My letter to me was far more effective than any of my words or letter to my AH.
If you are going to write him a letter, at least say what you mean. And mean what you say.
E.g. is it going to be enough for you that he "considers getting treatment". I considered winning the lotto last night but that doesn't mean it is going to happen!! And if you say you wont live with alcoholism - you need to mean that. Empty threats compound the problem.
Best wishes.