I personally think a well thought out letter, delivered personally, is fine. I would not send a letter by email (it would not be worth as much and could easily be ignored for a while). So writing the letter, telling her you have something important to discuss, make a date and a time and sit down together (no kids, in fact, sending them to grandma's for the weekend would be a good thing), hand her the letter, then be prepared for either a long talk or for her to say "I need to absorb this" in which case, you can agree to come back together at another pre-arranged meeting.
I really do understand your fears about being around your kids everyday and the thought that divorce would disrupt that. That is (essentially) the same reason I didn't leave my husband until our kids were 14 and 18. But what I didn't realize during that time was that I was showing my kids a very poor example. From what you said above, you do realize the dangers in showing your girls a bad example so I won't harp on that point any longer....it is just something to really keep in mind. Because after another year or two, if you and your wife still have not had sex, your resentment for her is going to be oozing out of all of your pores and your poor girls - no matter how you try to shield them from it - they will internalize that resentment and they will feel all the emotions you and your wife are not saying out loud. The white elephant in the room can be ignored by the adults, but the kids will see it and trip over it every day.
Anyway....your case is not hopeless! You definitely need encouragement and you will both need counselors, probably individual as well as marriage counselors, to get through this. But you can make it if you are both willing to give it a try.
I wish I had found this community or at least the books when my marriage was finally at the breaking point. Or I wish my ex-h had found them and initiated the ultimatum to me, as you are probably about to do. Because I really think we could have fixed it, and we were worse off than your marriage is (long story, full of pain and nightmares). So do try to have hope.
The one thing that will help you more than anything else, is to forget the notion that your wife "knows" she is doing this to you. I said that before, and I know this is very difficult for the HD spouse to understand, but she really doesn't know. She would not do this to you if she did know. Please just try to change your thinking on that one point and adopt the idea "she just doesn't know". This will help you with the resentment if you can really absorb it. Plus it is true! So I hope you will be at least a teensy bit happy to know that she doesn't know, versus that she is so mean and vindictive that she would purposefully hurt you, reject you, and manipulate you. Be happy that the truth is NOT what you believe, please!
I was a LD spouse and I have had many women friends who were or are LD, and not one of them EVER has said "yeah my idiot husband, I can jerk him around soooo easily, and I just love rejecting him for my own sick pleasure". OK? Trust me, she doesn't know what she is doing to you.
If and when she does realize it, it will break her down.
During my marriage, I never realized it. But after my divorce, after the healing and the pain and all the bad things that go on, splitting the assets, telling the kids, on and on until you dont' think you can handle one more day of it...and then finally you heal just a little tiny bit, and then after that - - THE TRUTH hits you in the face like a baseball bat. When I finally saw the TRUTH of how much pain I had put upon my ex-h with my rejection, how it made him feel worthless and ugly....I think I actually threw up that day. I had no idea. And even though we are divorced and I do not love him anymore, I would go back and do it over if I could, because that was NEVER the message I had wanted him to receive from me.
I hope to help convince you that your wife doesn't want that message to go to you either...although, I know that you won't believe it today. Maybe if you stick around and keep getting helpful tips and advice you will see the truth of that matter.
