My little sister (17) passed of an accidental overdose this week. how do i do this.

Im only nineteen. And she’s only seventeen. and it’s daunting to think eventually I will have lived most of my life without her than with her. To start, my sister started to become addicted to pills when Covoid began, she was around 14yrs old. Since then I have watched her be whisked away in an ambulance multiple times on the brink of death, i’ve researched treatment centers and dropped her off at them, i supported my parents through trying so hard to save her. I basically started to become a second mother to her because we didn’t live with our dad and my mom worked so often. I tried so hard to save her, we all did. My dad and I found her together, some friends and I were going to stage an intervention that morning, and she was going to start living with my dad for a bit because my mom was so beat down from my sister relapsing, stealing, and lying. I can tell my father will never stop beating himself up for her having died in his home. i keep telling them, she takes street pills alone in bedrooms, she was constantly putting herself in this position and it could have happened anywhere, honestly including my own apartment . I knew her better than most people. She told me she was going to keep doing drugs until it killed her and she told me that just a couple months ago. so i find some peace in knowing that in a way she got what she wanted, peace and quiet. she was deeply troubled and had PTSD and bipolar disorder. After she passed, i started to really look at those baby photos and tell stories and i just, i realized maybe she was never meant to grow up. like a lost boy in peter pan. the older she got the more terrified of the world she became and she never had any interest in the parts of life that come with growing up, but i always did. she loved to be a kid, and i think when she felt like she had to start growing up the world became a place she didn’t want to live in. It’s now Tuesday, she passed on Friday and i just feel so numb but i miss her so much. It just brings me peace that she never has to grow up and will now be forever young, hopefully with her cat , of course im convincing myself there’s an afterlife. although i’d give anything to have a chance at growing old with her. her and i were so close. but because of that i know she now has the peace shes craved so desperately . i just now have to take care of my parents, both of which have always had pretty fucked up mental health. if you have any advice on grief, supporting parents, or just idk, i’d appreciate any words. i don’t know how to do this, everyday i just wake up, remind myself she’s gone, and i try my best. she’s always gonna be my beautiful baby sister, and i’m always gonna miss her.