Navigating a relationship change with my sister

I'm 22 my sister is 17. She's moving in with me as she's struggling at home with our mum and brothers who make the house a toxic environment for her with drink and drugs and criminal activity. She's become very withdrawn and depressed and she attempted suicide 3 months ago. I'm moving her in with me. I have 2 children aged 2 and 3 too. We are sisters and I have to help her I can't leave her in that house and wake up one morning to the news that she is dead. What I'm wondering is how do I navigate the relationship change. I'm still her sister but I don't want to treat her like a kid or be like her mum. But I don't want her to just fall into a habit of me clearing up after her etc. How should I approach the conversation about boundaries and house rules? I don't want to seem like I'm controlling or bossing her around either. What should I do?