Hi, I would like to help you with your question.
I understand your feelings about your father. It sounds like from your description that he has not been there for you but wants you to be there for him. It is very self centered to not consider how you would feel about meeting his new finacee and how you feel about his new family each time he has a one.
You do not have to feel guilty about not having contact with him. There is no where that it says that you need to subject yourself to someone else's mistreatment. You said you have forgiven your father, and that is great. That is all you need to do and all you can do.
Next time he contacts you, tell him again about how you feel. Simply let him know that you wish him well, but you have no desire to meet his new family and you do not wish to be part of his life. If you want, let him know you have forgiven him for what he did to you and your family, but you want to move on with your own life. Then hang up.
If he contacts you again, repeat what you said. Tell him you already said how you feel and you consider the relationship done. Repeat as necessary until he stops calling. It may take him a while to understand, but he will get it.
Consider therapy if you feel this issue bothers you too much. You may need to work out your feelings about what you experienced in your relationship with your father. Sometimes it can help you gain closure on an otherwise painful part of your life.
Please let me know if you have any further questions. I hope this helped,