You know - I almost always agree with what Toots posts, but this time I am going to have to respectfully dissent. I think the email needs work but I think the message actually needs to be conveyed. Old Dog and his wife are basically separated without the benefit of any formal child custody arrangement. So the way I see it, there is a need to clarify their informal one.
OD - you see the kids about 4 days a month, right? It seems completely reasonable to me that your wife respect that time. Of course, your boys are at an age when they have their own lives, and of course their wishes should be respected as well. I would approach any communication in that light and with that tone: "Wife - I am seeking to set up some structure to our informal arrangement to avoid misunderstandings".
I do agree about the tequila advice though.....and I would try a second draft of that email that sticks to the business of establishing a plan and loses everything else..