How can you think about your father in a good light if you found out he's a lying, cheating, manipulating, woman-beating man?

Look at him as a father, how was he to YOU? Was he mean and hateful unreliable  unavailable uncaring? Or was he generally happy to see you, gave you affection, & taught you things. No one is a perfect person, some imperfect people can still be loving parents. It is for you to decide to accept his imperfections and remember the way he is just with you, or reject the whole package with full judgement.