Divorce

My dad and step mom are getting divorced.... I’m 23 and my parents got divorced when I was 4. I don’t remember anything from their divorce, but this one is hitting me so hard! They don’t have any kids together, but her kids are my siblings. I love them all so much and I just feel like my family is being ripped apart! I’ve had my little sister all weekend and she doesn’t want to leave tomorrow, but I’m going on vacation and I can’t cancel it or take her with me.... I’m just so hurt and lost and I have no idea what to do! I want to be here and be strong for everyone, but I have no idea how to do that right now! I’ve never seen my dad so hurt. I’ve never heard my step mom sound so hurt. I’ve never seen my sister so quiet... she just left him today, so I offered to keep my sister an extra night, and my sister doesn’t want to go.... I have no idea what to do! Any advice would help right now as I don’t remember my parents divorce, so I have no idea how to help my sister..... I told my step mom that when I get back Thursday I can take my sister, but I haven’t heard back from her.... I’m worried that these kids will get bounced around and will lose the only family that they have 😔 I’m worried about what this will do to all of them! My sister has already said that she wants to move in with me, which I’m ok with, but I don’t want my step mom to take all the kids from me. I love them all! I just really need some advice on what to do and how to handle this.....