u/Hoes-Boats

So I 20f just found out that my dad 38m has another daughter. From my perspective growing up it was just him my mom and my sister who’s 9. Growing up my family dynamic wasn’t perfect my parents fought all the time it was traumatic and from then on as I got older I stopped liking my dad not fully but I lost respect for him. I have been out the house for 3 years and I just find out that my dad has another daughter who is 4. Which from my assumption my parents took breaks but never fully broke up we always lived in 1 house. When I was a kid till I was 19 he always supported me kinda and was there for me kinda. Our relationship was rocky. Once I found out I stopped talking to him as frequently before it went from 1 time a week to maybe 1 time a month I don’t even ask him for money or anything he just pays my phone bill now. He cut me off from all his credit card because of prior things. I found out 4 years later that I have a step sister and since then I haven’t talked to my father as much as I use to. I have now gone minimal contact am I wrong to be upset. He never gave me an explanation jsut a text message and a picture telling me this is my sister. After all these years of thinking ok maybe we aren’t the perfect family but at least from the outside perspective and as a kid it’s just me and my sister. My dad would do everything but have another child behind our back. Now we don’t have a good relationship we never did since I was like 16 and I kinda feel bad because I keep leaving him on read or delivered or giving him half responses because I’m hurt and upset am I wrong?