If the reality is as you have mentioned with regards to the relationship to your wife, your marriage conforms with the Shari`ah; because her being your aunt's daughter and a half-sister to your brother and a daughter to your father's ex-wife does not prevent you from marrying her according to the Shari`ah; because there is no religious text that prohibits it and the basic rule is permissibility.
If the reality is as you have mentioned, you used to swear oaths of divorce
repeatedly, not fulfill your oaths, break your oaths without intending to give divorce but to prevent your wife doing something, you have to offer Kaffarah (expiation) of a broken oath for every time you broke your oath. A Kaffarah of a broken oath is to feed or clothe ten needy people or free a Muslim slave. If you are unable to do so, you have to fast three days. It is sufficient for you to distribute five Sa` (1 Sa`=3 kg. Approx.) of wheat, rice, or maize, or the like of what your family eat to ten needy people, each one half a Sa` for every time you have broken your oath. If you do not remember how many times you have broken your oath, you may guess it and offer Kaffarahs according to the number of times you guessed. (Part No. 20; Page No. 123) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.