What is the ruling on committing adultery with a Christian woman who embraced Islam and gave birth to a child, and is this child mine, and what should I do in this situation?

You have committed a grave sin by committing adultery, and it is incumbent upon you to hasten to repentance. The child born to the woman is a child of adultery and is attributed to its mother, and is not attributed to the fornicator according to the majority of jurists, unless the fornicator claims paternity. You incur no sin by abandoning and neglecting the child according to Sharia, and you are not obligated to marry the woman, but if you wish to marry her, your repentance is a prerequisite.