What is the legitimate, Sharia-compliant way to atone for the sin of adultery that resulted in pregnancy, given that the husband and family are joyful about the pregnancy, and the woman refuses to abort the fetus or seek a divorce to marry the adulterer, and what about the child who will be attributed to someone other than his father?

The questioner must sincerely repent from the forbidden act of adultery, which is even more prohibited if committed with a married woman. Repentance involves avoiding everything that could lead to it again, and only repentance atones for this sin. He must also repent for ordering the woman to abort the fetus, and for ordering her to seek a divorce from her husband. Abortion is forbidden, as is inciting a woman against her husband (takhbeeb). The child is not attributed to the adulterer, but rather to the owner of the marital bed (the woman's husband).