Personally, I think it's a great idea, as long as it goes down the way you're describing it. You're telling him what you want and why, without threats and in a loving manner. You're also letting him choose the time and place for the discussion. One problem you identified with how these things went down before is that you always followed up with telling him what he had to do to to conform to what you wanted. There's nothing wrong with letting him know what you want from him.
One suggestion I'd have is that you change the script from "I cannot heal" to "our marriage cannot heal". You CAN heal, after all, even if your marriage fails. This is one of the points that, although you may not believe it right now, is really true. And when you really start believing it and acting like you've moved on, your H may take notice and start to realize what he'd be missing if you left.
Another suggestion is to not put too much pressure on the part about asking him how he thinks you two can get out of this mess. He may not have an answer, or he may not have one that you like. If he has an answer you don't like, will you be able to maintain your PMA during the talk?
Finally, set a time limit for the discussion and keep to it. My SBT MC called this "damage control", trying to avoid talks that go on without end, especially ones that have a tendency to get more negative the longer you engage in them.
