The wife can receive the Sacraments as long as she doesn’t remarry.
In the situation you describe, an annulment would like be quite easy, since the marriage may not have been valid from the beginning.
Suppose a person does not receive the sacraments. Can they still be saved?
Pardon me, but what in our doctrine, in our canon law or on God's earth would lead you or anyone else to believe that a years-long Catholic marriage that produces a child should get an "easy" annulment and was not "valid from the beginning?"
To put it another way, what church is it that you belong to that would so easily make innocent children bastards?
Those are rhetorical questions BTW. I know my catechism well enough to not be interested in your answer.
But that seems counterproductive. The man in this situation should bear 100% of the brunt of the trouble for doing this to his wife. She is now a single mother, through no fault of her own. If she meets a great guy that loves her son and wants to be with both of them, shouldn’t she be able to remarry without worrying about her immortal soul? Or she either cloisters herself and is alone forever, or she lives with the new man in sin.
None of these are acceptable to the reality of every day life.
What about shacking up with some dude, then? Is fornication a mortal sin?