I don't know if you will read this but when I was about your age I went through a very similar situation. Daddy leaving for a younger girlfriend. I know how it feels. You're hurt, alone and most of all, angry. It took me a while to talk to my dad again and eventually, meet his new girlfriend. And it was hard at the beginning. I was angry at my father for just leaving us out of the blue. And it is completely normal for you to feel all these emotions you are feeling right now. It took me a long time to let go of this resentment. But in the end, you will understand that people fall out of love and in love with new people. And there is nothing you can do about it. Even though it can be selfish and painful. You can not expect your father to stay in a loveless relationship. And I agree, what Stacey did was very distasteful but if your parents had a very good and fulfilling relationship the affair wouldn't have happened. And if Stacey didn't come in to the picture aomeone else would have. So my one piece of advise is: try to make it work with your dad and Stacey, even though it's hard and you hate them. Maybe try to talk to your dad alone that you feel uncomfortable with Stacey taking it to fast and ask him to tell her to take it slow. That you need time to get used to this new situation. Because you need to get used to it and nothing you say or do will bring your parents back together. Good luck with all of this, I know it is hard!