Does a divorce take effect if a man stipulated to his wife that she not bring smokers into his house or attend gatherings of smokers, and then it became clear that the maid in his house was a smoker, knowing that he expelled the maid and consummated his marriage with his wife thereafter? And can he retract this condition without informing his wife?

If the wording you uttered was, "If she were to go by herself to a woman's gathering where these grave sins are committed, then she is divorced," your wife is not divorced by the arrival of the maid, due to the non-fulfillment of the condition. However, if you intended to prevent the presence of any woman with these characteristics with your wife in any place, then divorce occurs upon the maid's presence. But if your wife brought her and was unaware that she smokes, or was unaware of this latter intention, then no divorce occurs. We advise caution against being lenient in uttering divorce.