I am facing a similar dilemma at present. In an ideal world, we would be able to share our feelings and get the understanding and support that we want but that ideal world is a very self-centred place and the reality is that we need to consider the feelings of others.
Lets be honest, lying about this sort of thing is not a good basis for a strong marriage, As Dena pointed out, the discovery of the deceit may make things a lot worse. You also need to consider the possibility that indulging in CDing while you wife is away may only give short term relief to your dysphoria but make it worse over the longer term, firstly because you feel that, having taken one step, you want to go further on the journey and secondly as you are forced to surpress your urges (in other words, the opposite of what you've never had, you never miss!).
It's very easy to say 'don't do it, lying and deceit in a marriage is wrong' but, as we all know, living with dysphoria is not easy and the opportunity to seek relief is often overwhelming and I think that many in your position, myself included, would have difficulty resisting the urge in this situation. In fact, as you have described it, being honest with your wife would end your marriage so there are obvious benefits to keeping quiet but, of course, are you just prolonging the agony?
To be honest, I think your bigger dilemma is what to do when your wife returns. Do you get rid of the stuff you've bought or do you hide it somewhere and run the risk of discovery? No marriage is perfect and, at one time or another, we've all done things that we've not disclosed as, I am sure, have our spouses. A little bit of 'cosplay' while your wife is away and then discarding the items (or, perhaps, going for a makeover at a trans-friendly salon) is probably harmless; however sustained deceit through hiding the items when she's back or having to mask increased dysphoria as a result of your actions definitely isn't harmless and you need to give careful thought to these aspects.
