Does watching pornography and engaging in sexual conversations make my mother fall into such acts, based on the principle of "as you sow, so shall you reap," and will my repentance be accepted?

The door of repentance is open. You must repent to Allah with a sincere repentance by immediately abandoning sins, regretting what has passed, and resolving not to return to them. You are not required to search for those girls to seek their forgiveness; rather, adhere to the Shari'ah and strive against your lower self. Sincere repentance prevents punishment in this world and the Hereafter, and none of your family members will be harmed because of your sins. Seek Allah’s help, associate with good people, guard your thoughts, increase in remembrance of Allah and supplication, observe the obligatory prayers and supererogatory acts of worship, and stay away from the causes of falling into forbidden acts. Trust in Allah’s forgiveness and generosity.