Abandonment

My dad cheated on my mum twice the second time was 5 years ago. I was in year 11 the same year my grandfather passed away and our house was flooded. My parents got a divorce and my father Maried the woman he cheated on my mum with. She has 3 kids. I didn't forgive him for a very long time, mostly because I felt he also divorced me and my sister. He made very little effort with us and spent every moment with his new wife and children. But I forgave, every time he let me down I tried again to make effort. The other day tears in his eyes admitted the distance, the grief caused and said he was sorry and moving closer to live closer to me. Then bombshell his wife is pregnant. He is 55, her not much longer. I was in shock. Still am. I feel selfish for feeling upset but he always used to complain about how tight money was but yet they have both spent thousands conceiving this child since my father got the snip a long time ago. I have had medical expenses I never asked any money for because I felt guilty and thought he was struggling. He thinks having another baby at his age is normal. He never wanted more children and even admits he doesn't know how to comfort me when I cry.... They even attempted taking in a child last year who was orphaned but took him back a few days later as he was too much to handle. I feel so uncomfortable. Ashamed. It's not that my father has moved on, or I'll have a half sister it's the age it's the way I thought he was finally going to make an effort with me and my sister finally but now has something else to raise to invest love in where we missed out. Me and my sister are adults now in our early 20s but our family dramas get more crazier and it tests my insanity so much. I just feel awful and confused