Shell, what you said about wanting your sons to have spiritual growth is great. You know...I was the type parent that always "talked" too much. Know what I mean? I have since learned that "showing" is much more important and just b/c the kids are not as small as they use to be....they will still try to be like daddy. You have such a great opportunity to introduce a whole new life to your children. As you find the right "times", you can talk to them. But, I talked an entire sermon to mine.....and that didn't go over big. So, I suggest that you pick the right timing and say what you feel would be a growing tool for them. When you decide to tell your boys about your decision to be baptized, that could be a special time to talk about spiritual matters. (But, I would make sure that there were no cells, TV, or other distractions.)
If I were you, I would tell your W before telling the boys or any other family memebers. That shows honor to her and it will (should) mean a lot that you chose her first--to give this special news. She knows that you certainly didn't have to tell her before anyone else, but you "chose" to do that. You know not to get all mushy or try to work on her emotions....or to take advantage and pursue with this new....you're just telling her something, and that's all.
Since you have time.....you can wait until you feel is the perfect timing and then tell her that you've made a personal decision that you wanted to tell her about. Then you can tell her that you are going to be baptized. Wait and give her a moment for the news to soak in.......and for you to see what her reaction is. If she asks any details, then you can tell her that the Church will have to set a date. See if she will ask you to let her know when it will be. If she does....that may be a good sign or it could be her way of finding something to say back to you. But don't allow her reaction to phase you one way or another. If she seems receptive to your news, I think you'll be able to determine how much to say. If she happens to not show any reaction, then I'd not tell her anymore than you were going to be baptized.
If she reacts in a positive manner, then when you are given a date for the baptizing...that will be something to share with her at an appropriate time. Bear in mind that a WAW carries around a lot of guilt, so be flexable to any kind of response from her.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!