Briefly, how do I atone for my oath of divorce and entering my wife's house, and does the divorce take effect by the entry of her family after this oath?

If you made your wife's divorce conditional upon her entering the mentioned house, then whenever she enters, the divorce occurs, and you cannot retract it. As for your statement, "you are forbidden," the ruling depends on your intention: if you intended divorce by it, then it is a divorce; if you intended dhahar by it, then it is dhahar; and if you intended an oath by it, then it is an oath. If by your statement, "you are forbidden," you intended a new divorce in addition to the first one, then two divorces occur upon entry. If you intended to confirm the first divorce, then only one divorce occurs upon entry. The matter depends on your intention. We advise you to consult the Sharia courts.