if a husband has went into his wife from rectum in the very early time there marriage, the husband has the information that what he is doing is wrong but he did not tell his wife and did this unlawful act. Couple of times, after 18 years of there marriage he remebered hios sin and wants to do kufara and repent this , the husband wants to know does this sin has effected his marrige , is their nikah become invalid? Now what should they do? What is the status of their children who were born after this bad act was done?

You may want to have this moved to the specific religion you are discussing, Since for most people there is nothing wrong for this act for husband and wife and many do it on a regular basis. And it is not unlawful to many. And is not a sin, in many religions.

So if you wish to report your post and ask for it to be moved to a specific religious area.