Okay, you're going to get a lot of responses from people telling you that you are within your right to cut him out of your life entirely. They're right, you have more than enough reason to never feel comfortable around him again.

However, I'd like to offer a bit of a different perspective (hopefully this isn't downvoted to hell and you get to read it). Being a pedophile simply means you are aroused by pre-pubescent children. It is possible to be a non-offending pedophile who is still a good person, with proper therapy. Being a pedophile does not mean you are instantly a horrible, horrible person, who deserves no love or family or friends. That being said, if a pedophile wants to remain non-offending, for the rest of their lives, then they really have to avoid any triggers and they need to be honest with themselves about who they are and what they feel. They cannot put themselves in positions that would prompt those urges and they should remove themselves from situations that cause those urges. That is not what your father was doing when he asked if you wanted him to teach you to masturbate. He was not avoiding harmful situations.

That being said, I have no idea what I would do if I was in your situation. I would ask myself if any specific details would change how I feel and maybe bring myself to ask him things such as, has he ever sought therapy for these urges? Does he still access those pictures? If he has sought therapy, has it helped? Does he still go? Why/why not? If he has not, why not?

None of those things might be important to you, and the answers to those questions might not mean anything to you, which is totally okay. It's also okay to care about someone who is a non-offending pedophile. It's okay to want to figure out a way you could have a relationship with him. It's okay to not want that. It's okay to not care about him anymore, also.