Perhaps this thread could be cleaned up a bit by the mods.
It has turned into much debating, rather than advice.
Mark, I still think your actual decision is about whether you want to be married to your wife or not, and whether you love her enough to spend the rest of your life with her.
How she takes to your conversion and whether she will still want to live with you, is a different question altogether, and one you need to ask her once you have made up your own mind.
Correct me if I am wrong, but it seems to me like a) you aren't happy in your marriage; b) you are looking for a reason to separate and c) your conversion to Islam may just be what makes your wife choose to divorce.
(Forgive me is I am wrong and I am speaking out of turn. Please feel free to correct me. Like you said you are the one who knows your circumstances better than any of us)
Please be honest with your wife.
If you don't want to live with her anymore as husband and wife, then tell her!
Your conversion to Islam doesn't seem to be the reason for your problems. The problems were there long before!
Any discussions around whether you can or cannot be married Islamically to your Christian wife are pointless, if actually you simply don't want to be married to her!
Be a man and tell her the truth!
I would hate it if my husband deceived me is such a way.
If you still love her - as you say you do - then show her that love and respect by being honest with her.