Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
If a man marries a woman on the basis that she is a virgin, then he discovers that she is not virgin, then there are two cases.
1) If he sets a condition that she be virgin.
In this case the scholars differ regarding his choices. The most preponderant opinion, however, is that he can nullify the marriage, if the reason of losing virginity is because of sexual intercourse. But if the reason of losing virginity is a violent jump for instance, then he has no choice, because the reason is other than sexual intercourse. Her Wali might not have been aware of this matter, and even this woman might not either.
2) If he did not set a condition that the woman be virgin, then he has no choice.
The Fuqaha (Islamic jurists) state that the choice is approved for the husband or wife who has the right to choose (on basis of a given condition) unless he/she does something that could be interpreted as an acceptance of the disadvantage or defect. So, since you stayed with her after you learnt about this defect you are no longer entitled to annul the marriage because of this defect.
But there is no doubt that you have the right to divorce her, in which case she is entitled to all her dowry in addition to her expenses being paid until the end of her waiting period. She has to observe the waiting period because the preponderant opinion of the people of knowledge is that your staying in seclusion with her has the same ruling as consumating the marriage.
However, if you see that you can be patient with her and keep her as a wife as a way of being kind to her, then surely you will get a great reward for doing so, especially since she was truthful to you.
Allah knows best.