How am I supposed to accept what’s happened? She needed me and I failed her, how do I live with this?

My mum was sick most of her adult life with multiple cancers that she was assumed to live for a maximum 6 weeks on the worst one that strangely she pulled through and lived another 10+ years. She had Lambert Eaton disease and Myasthenia Gravis among other illnesses. She had part of her lungs removed from other diseases, etc. She was constantly sick, constantly in and out of hospitals. There was never a period of more than 8 weeks where she wasn’t in an ambulance. Sometimes she seemed like she was stronger than you could imagine and others you could tell that she was so frail. Not once did she ever give up. She had a winning attitude at everything nothing could keep her down at least that’s what she convinced everyone she had 9 lives nothing could stop her even being disabled and unable to walk or breathe or make food or wash herself. She still didn’t give up. On her final period she had a heart attack and surgery and still got back home. She was then getting infection after infection and waking up screaming my name, that she was dying and to help. I couldn’t handle it. I retreated to my room and allowed her to sit alone most days even though I’d pop in and ask how she was. It wasn’t enough. I’d cook, clean, wash her, etc., but I didn’t do enough. Most days she was just sat in front of a TV by herself despite me being in the same house as her. I don’t want to make any excuses for myself but I’m struggling with life. I have personality disorders and I’m on antipsychotics. Her very final week she woke up screaming my name telling me, “I’m dying, I’m dying. Help!” I ran in and I couldn’t handle it I shouted at her and not as gentle as I normally would. I picked her out of bed and rushed her to the bathroom shouting at her she needs to stop this she’s not dying etc. she was slumped on the toilet struggling after that I did the same into the living room where she spent most of her days on a couch alone I kept shouting at her she told me she couldn’t breath and she was dying. That day I didn’t give her oxygen didn’t check her stats didn’t sit with her didn’t make her a wee coffee nothing by the time I woke up again she was already leaving with the ambulance and I never got the chance to speak to her properly again. She died some days later and I can’t feel her anymore I really need her to give me a sign before she goes forever how am I supposed to live with the way I treated her on her final moments I was just angry and scared I solo cared for her for years watched her decline listened to her struggles took her to appointments etc. I was angry and didn’t know how to handle it I was depressed and instead of making more effort with her I gave up and did the bare minimum. She deserved so much more. My best friend is gone forever and I miss her so much. I’m not even grieving in a negative manner, I just realize what I could have done better and I need to live with these realizations. I know 99.9% of us would do differently if we could foresee the future but unfortunately we don’t get that opportunity. Every day I’d make sure she was fed washed had her oxygen took her meds etc. but I never spent time with her despite being in the same house. All because I’m socially awkward I don’t really know how to talk to people not even my own mum and it always made me feel horrible. It’s just a horrible realization that I COULD have did more for her. I have texts from her over a few month period where she was sending me hints as to her leaving and I didn’t even watch the little videos she sent me until she passed because I buried my head. Some of our last messages she told me how brave I was and how much she was proud of me and she knew how much I loved her and she’ll always love me no matter what. It’s hard I haven’t felt her presence yet, it’s only been a little over 24 hours. I just thought she’d have visited me by now.