My Sister (34F) Just Died, the Situation is a Mess, How Can I Help Her Kids?

This is unfortunately a complicated situation and my heads spinning.
First things first, I?m (20F) adopted. I was adopted and birth but at the age of 7 I met my biological siblings Mark (38M) and Britney (34F). My bio mom passed away before I was able to meet her and my bio dad is in jail. I apparently look like I could be my bio moms twin.
I have/had an awful relationship with both of my siblings. The older I got, the less I seemed to like them. After an argument in 2018 we basically had no contact until 2019 when I became homeless and called Mark begging for a place to stay. He told me I could stay with him, his new girlfriend (he?s a serial cheater), and their kids (12m)(13f)(.5F). It was a tough transition for me as I?m from a beach area and they live in the literal desert but I was just happy to have a roof over my head.
Living with my brother was hell. I watched as he came home drunk every night, and picked arguments with me over everything. I wasn?t allowed to use the kitchen, the fridge was off limits and I couldn?t use their washer and dryer. After being there for two days they told me I was a freeloader and needed to pay them $800-1000 in rent a month as well as only take 5 minute showers. I just moved to a brand new location without much notice, I didn?t have a job yet. I was going through a lot of things and almost had a breakdown.
My sister Britney called as she lived only twenty minutes away and said I could crash at her place for a few days to get away from our brother for a bit. I was excited, and gladly said yes. When I got to her place I realized she only wanted me there to be a free babysitter so she could sit around and get high all day. I put up with it because I love her kids Bailey (13F), Rose(7F) and Zach(1M). She ended up stealing my keys and using my car and was gone with her boyfriend Chet (31M) for hours on end. Leaving me alone with her kids.
I don?t know a thing about taking care of a baby or making dinner for children or hell. I don?t even know how to entertain them longer than an hour. I was also extremely depressed and honestly was at my lowest point i?ve ever been at. I?m not a good babysitter and there was a lot of struggling but I love those kids so ****ing much it was fine. My sister was then gone for hours, and those hours turned to days. I didn?t have my car, and I was alone in a house with three kids and three dogs. About a week later (no one could get a hold of her), Britney and Chet came back to the house as if nothing happened. Her eldest Bailey told me this happened a lot and I shouldn?t be upset.
When all the kids went to bed I got in a fight with Britney and basically called her an irresponsible parent and she needed to be there for her kids because they need their mom. I can?t remember quite what was said but she was upset and called me a spoiled brat. She called our brother sobbing and told him I had attacked her (???????) and was a threat to her and her children, she wanted me gone from the area. So Mark told me I had two days to pack my **** and get the **** out of his house. I was sobbing, the girls were crying as they didn?t want me to leave and I felt horrified they were dealing with all of this.
I wasn?t allowed to sleep in either of their houses while I packed, so I had to sleep in my car. Now i?m back in my beach area in a home with friends and I?m happy, I hadn?t spoken to my siblings since that time. Well, until last month that is when my brother called me out of the blue. I answered and he told me Britney was in the hospital in a vegetative state. She OD?d on some pretty heavy drugs. About 12 hours later she passed away. I didn?t cry, I don?t know why.
Now here comes the bad part. Each of her kids has a different dad. When she passed, each dad took their kid, police were involved and there was lots of fighting. Zach is with Chet in the desert. Bailey went with her dad Frank (32M) and is living in a suburban area two hours north of the desert and Rose is with her dad Mike (30M) two hours south of the desert. They?re all split up and I feel awful. Fast forward to the funeral, when I go I?m shunned. People tell me I shouldn?t have come and that I?m an unwelcome face. My brother tells me to **** off for trying to ruin his sisters funeral. All I did was show up to MY OWN SISTERS FUNERAL???
All of Britney?s kids were there, Zach obviously didn?t remember me but seeing the two girls made everything worth it. Rose didn?t leave my side the whole day and Bailey sat next to me the whole time. I think because I?m young they view me as the cool aunt? I don?t know but I love them so much and I know they care about me. It was really hard seeing them as Bailey was the one making sure everyone else was okay. After the funeral I pulled her aside and asked how she was and she just broke down sobbing and all I could do was hug her. When it was time for me to go (I had a long drive home to work an opening shift the next day) Rose started crying and begged me not to leave her and that she misses me and her mom. My heart was breaking.
I gave both of the girls my number and told them to reach out if they ever need anything. But I?m the adult, it?s on me to make an effort so they know I?m here for them and on their side throughout it all. I don?t know what to say or how to reach out? Rose called me yesterday and just said she missed me and wanted me to visit and play Roblox with her. I literally have no idea what that is but I think it?s on the phone so I plan to download it to play with her. She sounded happy to talk to me but I couldn?t talk for long as I was at work. There?s such a distance between me and then and I want to be there for them but I don?t know how.
I don?t want to seem creepy or weird or strange or put them in an uncomfortable situation all because I wanted to say hi. I don?t want to force bonding with them or anything like that, but my heart goes out to them. The rest of my bio family can go to hell for all I care but I love those three kids. I?ve accepted that I?m more than likely not going to have a relation with Zach but the girls I feel I still can? I just don?t even know where to begin, what do I say. Do I even reach out or is that not my place?? I don?t want to overstep anything but I want to be in their lives. I?m their only aunt.
Maybe I?m so hell bent because my father (adopted) died when I was 12 and I know what it was like to have your entire world ripped apart in the span of two minutes. I feel like I can be the person to them that I so desperately needed? I don?t know I?m rambling. Any advice would be much appreciated in this situation, it?s all very out of my element. sorry for how much i wrote.
TL;DR: Sister died recently, her kids all got split up. How can I be there for them in this time?


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