It is not desirable for a woman to name the baby without consulting her husband. Such decisions should be made by mutual consultation between husband and wife. So, your wife is mistaken in acting alone.
Now, you have a choice of accepting the fact, or agreeing upon a new name that is acceptable to both of you. I would advise you to forgive her, as long as the name she has chosen is not objectionable in Islam.
If, on the other hand, the name is not acceptable, then you ought to change it. However, you cannot simply act alone; both of you need to agree on the new name.
Remember a successful marriage is based on consultation and forgiveness. I pray to Allah to grant you wisdom to save your marriage by developing positive attitudes.