Avoid discussing sex toys with your wife unless you use the doll together. When you tell her about your obsession, she will likely ask you a lot of questions. Please remain patient and try to answer each one in a calm, normal voice.
If your wife has her own collection of best sex dolls, half the battle is over. She'll likely understand why you use life-size shemale sex dolls and won't make you feel weird or embarrassed. The only thing you should be careful about in this situation is not to judge or make fun of her sex toys. If you do, be prepared to accept some compensation, which can unnecessarily complicate the situation.