Losing both of my parents

I don't know if it's okay to make a post like this? I've never made a thread before... But I'm struggling at the moment and I have very few people I can talk to about things. I just really need to vent.

So I lost both my parents a year apart. In completely unrelated circumstances. My dad passed from lung cancer just over a month after he was diagnosed, and it was devastating. I was with him when he died... It was the most traumatic day of my life. So far.

Every day I think about how things might have been different if I'd visited him more. Maybe then I would have noticed his horrific and dramatic weight loss. I would have realised the extent of his extreme back pain that he would downplay any time it came up. I could have pushed him to go to a hospital, where they would have seen that it was being caused by the massive tumour on his lung pressing against the nerves in his spine.

I lived two roads away from him.

Two.

And I hadn't seen him in months.

About a year after that and I get a knock on my door. My mum has died. I'm told it was peaceful, that she was probably sleeping when her high blood pressure caused the fatal bleed in her brain. But it doesn't feel real. I didn't see it like I did with my dad. And I never saw her again, she was just... Gone.

I was going to ring her earlier that day but it slipped my mind. I just forgot. But what if I had? Would she have been able to tell me that she was feeling unwell? Would I have noticed that she seemed off? Would there have been time to save her?

I remember a conversation I'd had a couple of days prior, with her best friend who she lived with. My mum had seemed confused, slurring her words and not being able to focus. Her friend made an assumption at that time, that she had likely mistakenly taken two of the very strong painkillers she was on instead of one, and I believed it. She slept it off and when I called her the next day she seemed fine again. That would be the last time I ever spoke to her.

I hate that her friend suggested that. I hate that I didn't push it further because it was a 'good enough' reason for me. I don't blame her, but it's something my brain won't let go of, no matter how hard I try.

Every day I fight with the guilt, the vivid mental replays, the 'what ifs'. It just never stops. It's been almost 3 years since I lost my dad, and almost 2 years since I lost my mum, but I feel like I'm frozen in time. Doomed to relive it in my head every day until the day I join them.