What is the ruling on one from whom sexual fluid was discharged during the farewell circumambulation (Tawaf al-Wada') after he followed a woman, then sought forgiveness, performed a ghusl, and completed his circumambulation? And what should he do?

You must initiate sincere repentance, frequently seek forgiveness, and perform righteous deeds, as you have committed a grave sin in a blessed place. Your first circumambulation (Tawaf (definition)) is invalid due to your intentional state of ritual impurity (hadath (definition)). After performing the ritual bath (ghusl (definition)), you were required to start the Tawaf anew. You are in a situation similar to one who has omitted the Farewell Tawaf, and therefore, a sacrifice (dam) is obligatory upon you (the minimum being a sheep slaughtered within the Haram (definition) and distributed among its poor). Your Hajj remains valid.