What is the status of a man who fathers a mamzer?

Question

Please consider the following: A Jewish man who is not a mamzer engages in sexual relations with a Jewish woman who is not a mamzer but who is legally/Jewishly married to a different Jewish man. The married husband and wife do not engage in sexual relations and the woman exclusively has sex with the man who is not her husband. The woman and her lover conceive a child that is, with certainty, born a mamzer. What is the resultant halachic status of this "lover" who illicitly fathered this child with her? Does he, the father of the child born a mamzer, also become a mamzer? If not a mamzer, does he carry some other negative status that would affect subsequent Jewish children born to him?

In short:

Father --> Not a Mamzer
Mother --> Not a Mamzer, but married to someone else
Offspring of this forbidden union -- Mamzer

Does the fact that the father created a mamzer reflect on him in any way? If so, can that affect other (non-mamzer) children born to him?

Answer 1

Neither parent becomes mamzer.

The man does not be changed because of this act. The definition of mamzer according to The Halacha is a man who is born from a prohibited relationship between two casher parents but the relashionship is prohibited by karet (nidda is an ecception to this rule) or punishable by death. A second case is the fruit of the relationship of at least one mamzer.

Source: Mishna in Kiddushin 3, 12:

... Wherever there is [a valid] betrothal and there is a sin, the child follows the defective one. Which is this? ... a mamzeret [the female offspring of certain prohibited relationships who may not marry into the general Jewish population] or a Netina [female Gibeonite] to an Israelite, a female Israelite to a mamzer or Netina. [With] any [woman] for whom there is no betrothal to him, but there is betrothal to others, the child is a mamzer. Which is this? This is one who has sexual intercourse with any one of the forbidden sexual relations [mentioned] in the Torah.

See in Shulchan Aruch Even Haezer siman 4.