Am I obligated to marry a girl who concealed her tuberculosis infection, despite my repeated inquiries about the reason for her thinness and her initial denial?

The essence of the fatwa: If the relationship is merely an engagement, you may annul it because it is a promise of marriage. However, if the marriage has been contracted, you do not have the option of annulment due to tuberculosis, as jurists have not established the option of annulment for every illness. You have the choice between retaining her and seeking her treatment, or divorcing her kindly.