What is the Shar'i ruling on shunning a mother who abandoned her son after giving birth to him out of wedlock, and does that affect the acceptance of good deeds?

You must repent to Allah for disobeying your parents. Filial piety towards your mother continues after her death by supplicating for her forgiveness and mercy, as the Messenger of Allah, peace and blessings be upon him, said: "When a person dies, all his deeds come to an end except for three: a continuous charity, or knowledge from which benefit is gained, or a righteous child who supplicates for him." Also among what has been reported regarding honoring one's parents after their death are: praying over them, seeking forgiveness for them, fulfilling their pledges, honoring their friends, and maintaining ties of kinship that are only related to you through them. You should also increase in righteous deeds, not despair of Allah's mercy, and beware of Satan's whispers to abandon religious duties or consider suicide.