ANSWER:
You must break off all communication with him and block him off completely. There is nothing you can do about him having your pictures. All you can do is repent to Allah while showing deep remorse and sincerity and ask Allah in the sujood of your prayers to conceal for you your sins. If you contact him or even beg him for these photos, he will ask you to become his ********* and he will get his friends to take more photos of you and use you! There is no other choice but to block him and ride out the storm while enduring the consequences and make a lot of duaa to Allah.
You may have to inform your father so that you do not become a victim of his blackmail.