Will anything be incumbent upon me if I marry the girl about whom I said, "She is forbidden to me in this world and the Hereafter"?

This statement from the girl constitutes ẓihār, and it is permissible to marry her, but it is not permissible to have intercourse with her until she performs the ẓihār expiation. The reason it is considered ẓihār is that the wording implies her permanent prohibition. If a man says to his wife, "You are unlawful to me," and he intends it to be in all circumstances, then he is a muẓāhir (one who commits ẓihār). However, if he intends it for a specific instance, or if he makes an unqualified statement, it is not ẓihār.