Maybe go see a counselor? I'm sure your wife will insist on a Mormon counselor which I think is okay, you can use that to your advantage. There probably is a way to interview a counselor before committing to regular visits, but I'm not sure how. Maybe just you meeting with them and telling them what you want and asking him if he can help you and your wife. As you've made clear above, you want to be yourself, and you want your wife to be okay with that. Some questions that seem worth asking: "Do you believe that it is morally right for a believing member to divorce their no-longer-believing spouse?" "Would you be able to explain to my wife why the LDS church would encourage an exmo and a Mormon to not get a divorce?"
Basically, whether it's just you or both you and your wife, a counselor will teach you more strategies of communication. There's lots of subtle things about sensitive communication that a lot of people don't know. Also, if one method of communication isn't working, there are alternatives. The counselor will start with what he thinks will work best and more down the list until you find something that works for you.
My two cents. If you want your wife to stick with you through your transition, you better make sure that she wants to. I think the first step is to make sure she's in love with you, which is more than simply loving someone. Does she find you physically, emotionally, and intellectually attractive? Do the two of you make time to go on tantalizing date's? If there's any doubt, you might want to focus on that before making your wife come to terms with your apostasy. The only other thing that could hinder your wife's desire to be with you after your transition would be her religion. Only someone she trusts (in regards to religion) will be able to convince her that it's okay that the two of you be together and I think an LDS counselor is your best bet.