I feel ya man. Just open up to her. I talked to my wife this past week on vacation about steroids, possibly wanting to compete and going on HRT. I told her that ever since I was 19 and 20 years old and working at Levrone's gym that I wanted to at least compete in the Mr. Maryland contest which is where he got his start. I said I know its late being 33, but time has gone by so fast with the birth of our kid; I don't want to look back when I'm 50 or 60 and say "Damn I wish I did that."
She said if its going to make you happy than do what you need to do and I'll support you. I said it was going to involve taking a lot of gear and she was cool with it. She knows I do my research and spend a lot of time on the boards here. She worries about my health, and if the roles were reversed I'd worry about her's. As we continued to talk more about it, after she has a second kid, I may have talked her into a low dose Var cycle.
Bottom line, you have to be honest with your wife and at the same time be yourself and make yourself happy. If she can't understand that (if this truly is important to you) and want you to be happy, maybe re-evaluate everything.
I was nervous as hell approaching my wife about this, a bottle of wine at dinner and a few after dinner drinks helped. In the end, I feel through that conversation we grew closer as a couple. Just talk to her and be honest, she'll see the sincerity and hopefully be a bit more understanding.
At this point though, she caught you doing something behind her back so her mind will automatically go to "What else is he doing behind my back?", which is also why she's probably so upset. It not entirely about the juice.