If you really want to tell the other person something and can't get it out at one time while sober, have you considered maybe composing an email and taking your time doing it -- writing a little, saving it, editing, adding, etc, until it seems to say what needs to be said? I've had some success with that at times, though it can get a little obsessive if it turns into a week-long project (ask me how I know).
Stay strong!