How to handle doubt about istekhara result after negative information about wife’s character?

Muhtamim, Asalamualikum. I am writing you from Bangladesh. I am a lawyer in profession. I am in big problem regarding conjugal life. I got married on the 14th January 2009. Before getting married I had Istekhara done by two persons. Results were positive in both istekhara according to the persons who had it done. I did not do any istekhara by myself. But I always prayed to get a wife as a gift from Allah with the qualities which I desired and with the qualities which Allah deems proper and fit for me. Unfortunately I did not get which I prayed. In addition to this, recently I have heard a very negative message about my wife’s previous character, which she and her family have completely hidden to me before getting married. After hearing this message it would be too tough to continue a normal and easy conjugal life for any human being. I am also no exception to this Now I doubt about the result of istekhara done by two persons and prayer which I did myself. I don’t know how the persons did the istekhara for me. It is not possible for me to stay with them during the istekhara. So I had to believe them. After all both of them are Imam of mosques. But I myself prayed to Allah. There is no doubt. In this circumstances I am very confused about what I should do. So would you please answer the following questions? 1. Since I did not get what I prayed, so can I still deem my wife as a gift of Allah? 2. Can I reach in this decision that my prayer has not been accepted by Allah in the way what I prayed? If it is so, then she is not a gift of Allah; isn?t it? 3. If she is not a gift of Allah, can I divorce my wife for the reason of that negative message? Though I had istekhara done and prayed by myself for a gift. 4. If she is indeed a gift of Allah, then how can I continue my conjugal life with her tolerating such a negative message about her character? 5. According to Quran and hadith on which grounds one can divorce his wife? Would you please clarify completely the matter and let me know what I should do now?