She said to her husband: You are haraam to me until the Day of Judgement

If a wife says to her husband, You are haraam for me, or you are haraam until the Day of Judgement, that does not result in zihaar or talaaq, because zihaar and talaaq can only be done by the husband. Rather it comes under the heading of making what is halaal haraam, such as stating that some kind of clothing or food is haraam. When breaking this oath she must offer expiation for breaking an oath, because Allaah says (interpretation of the meaning): 

“O Prophet! Why do you forbid (for yourself) that which Allaah has allowed to you, seeking to please your wives? And Allaah is Oft‑Forgiving, Most Merciful.

2. Allaah has already ordained for you (O men) the absolution from your oaths”

[al-Tahreem 66:1-2]

So Allaah has described making haraam something that is halaal as a kind of oath. 

The expiation for breaking an oath is freeing a slave, or feeding or clothing ten poor persons. The one who cannot do any of these things must fast three days. 

She only breaks the oath if her husband has intercourse with her when she is willing. 

Shaykh Ibn Baaz (may Allaah have mercy on him) was asked: If a woman says to her husband, If you do such and such you are haraam for me like my father, what is the ruling on that? 

He replied: If a woman says she is haraam for her husband or she likens him to one of her mahrams, that comes under the same ruling as an oath, and does not come under the ruling on zihaar, because zihaar can only be done by husbands to wives according to the text of the Qur’aan. 

In that case the woman must offer expiation for breaking an oath, which is to feed ten poor persons, giving each poor person half a saa’ of the local staple food, which is equivalent to approximately one and a half kilograms, giving them either lunch or dinner; or clothing them in garments that are acceptable for praying in, because Allaah says (interpretation of the meaning):

“Allaah will not punish you for what is unintentional in your oaths, but He will punish you for your deliberate oaths; for its expiation (a deliberate oath) feed ten Masaakeen (poor persons), on a scale of the average of that with which you feed your own families, or clothe them or manumit a slave. But whosoever cannot afford (that), then he should fast for three days. That is the expiation for the oaths when you have sworn. And protect your oaths (i.e. do not swear much)”

[al-Maa’idah 5:89]. 

If a woman makes haraam that which Allaah has permitted, it comes under the same ruling as an oath. The same applies to a man making haraam that which Allaah has forbidden, except his wife, because Allaah says (interpretation of the meaning): 

“O Prophet! Why do you forbid (for yourself) that which Allaah has allowed to you, seeking to please your wives? And Allaah is Oft‑Forgiving, Most Merciful.

2. Allaah has already ordained for you (O men) the absolution from your oaths. And Allaah is your Mawlaa (Lord, or Master, or Protector) and He is the All‑Knower, the All‑Wise”

[al-Tahreem 66:1-2]

End quote from Fataawa Islamiyyah (3/301). 

The wife must repent to Allaah for saying this, because making haraam what is halaal is not permissible. 

And Allaah knows best.