Take a look at all the posts by our female members, and I think you have the right answer. If you want a strong relationship with your wife that's built on honesty and trust, you'll tell her. If you're afraid that she'll still say no, and steroids are more important to you than your marriage, go ahead and lie. IMHO, I think the choice is clear.
On a personal note, I spoke to my wife before I started using, and I bought the book "The Testosterone Syndrome" by Dr. Shippen. I let her read portions that she found of interest, got bloodwork, etc. and made her an informed part of the process. I just think that's the way it should be with ALL areas of your marriage. You may think you can compartmentalize things, but a healthy relationship does not do so.
Good luck bro on whatever choice you make.