HI Debbie - you don't say here, but I'm guessing you have been married for quite a while, and this dynamic has been going on for quite a while as well. Perhaps you've gotten used to it, the hiding, the deception.
It's not that you are not brave, it's that you know that if you come out, things will change. The good news is that you care enough about and for your wife that you wish to shield her from all this CD stuff and maintain your relationship. Maybe you are embarrassed too- I know I was. The bad news that the longer you continue like this, the longer you are deceiving her, lying essentially. And that may be an even bigger point of contention than revealing your crossdressing.
However, I think you are getting weary of this too, and need to make a change, for better or worse. Otherwise, you are basically living a lie, and you know it.When I realized that, I knew I had no choice but to come out. I'm one of the lucky ones, my wife was accepting and seems to be getting more into it as time goes on...I couldn't ask for more. Maybe you will be too, but if not, at least you will be living honestly.
So the biggest question of all is can you continue living your life this way? Is it fair to you and your wife? The answers to those questions will tell you how to proceed.