What is the right course of action after donating an egg to a friend, which resulted in a child, given that the act of donating is forbidden?

What you did, donating an ovum to another woman, is impermissible and forbidden, as scholars have ruled. If you undertook this out of ignorance, then there is no sin upon you. However, in the future, you must ask those knowledgeable about matters whose rulings you do not know, in compliance with Allah’s saying: "So ask the people of the message if you do not know." As for the child resulting from this procedure, that is a matter that requires direct consultation with scholars regarding its details.