Have been debating this

Sorry, long post but in need of advice and comforting words. Okay, first off- my parents divorced when I was three and my sister was six. I'm now almost 24 and sister 27. It wasn't as hard on me since I was younger and didn't really know what was going on. Since then, my dad has had many girlfriends and married & divorced three more times. So yes, a total of FOUR marriages and divorces. I'm not okay with that. Here's the real story, his second marriage was right after my mom and didn't last long. So I don't remember much but do remember the worst thing that has ever happened to me and my sister. From that marriage, we had one stepsister and one stepbrother (I don't like using those terms at all for the upcoming reason). Wife #2's daughter (the stepsister) was in her teens and very inappropriate with my sister and I. I was like 4-5 and my sister 7-8. There was never any penetration but a lot of kissing and touching. She made us touch her boobs, vagina, and made out with us all the time. It f***ed me up, made me think that it was okay. I was FOUR, an innocent little girl. (I'm 100% straight btw) My sister and I (and her) have been the only ones to know about this up until about six months ago. My dad called me one day (last November or so) and had told me he had been spending a lot of time with Kris (wife #2). I was crushed, pissed off, and thought how can this be happening. I thought I'd never have to think about that awful experience again and never talk about it again. But every time I talked to my dad the horrible memories came back to me. So I stopped calling him and when he called me, I made it short and always had something to go do. Finally (about six months ago) my sister talked to him and told him everything. She said he seemed pissed and that he said he felt like he failed as a dad. But it didn't matter to him apparently, because he's still with her! He never ever mentioned the topic to me even though he knew everything. He even had the balls to bring her to my freaking wedding without even asking me! Livid, I have been livid. Anyways, he finally texted me one day to ask why I haven't talked to him and I came unleashed. Told him everything and asked how the hell he is okay with the situation. He acted like nothing ever happened! He said, oh... Well I didn't know it happened to you too. Hello!? You knew it happened to one daughter but not the other so it's still okay?? He lied to me because he knew everything that happened. I had never even told my husband about this, afraid he'd think differently about me. About a month ago, he saw the texts from my dad and asked. So I finally told him. He was the best, comforted me and was very sympathetic. But he immediately was beyond pissed at my dad. He called him and they did not have a pleasant conversation at all. I'm not mad at my husband for anything he said because it's exactly how I feel too. We have not talked to my dad since. My sister has, she's more of the peacemaker and wants to get along. But I can't, I speak my mind and that's how I feel. Told my dad I can't talk to him or be around if he's still going to be with wife #2. That's just how it's going to be and I can't budge about this sort of situation. And of course, he's been lying to his side of the family about it. He's always been a compulsive liar. Am I wrong? Am I crazy? I haven't even told him I'm pregnant again. (14 weeks along and we have a 3yo too) It'll be interesting when our 2nd baby comes and when my sister gets married in June. Just my question is, how in the hell can my dad be okay with this!? Ugh, thank you for reading. I would really appreciate your advice.