When I first read your post OP I felt vitriolic and angry on your behalf, based on my own experience of grief. And then I checked myself. And that's my point.
My mum died very suddenly when I was 26. Two weeks later I had a miscarriage and broke up with my partner. Some people were ace, some were monumentally crap in numerous ways: ranging from my boss who said disapprovingly "I don't think I'd be this distraught if my mum died" to the friend who, despite not knowing my mum at all well and not having seen her for years, wanted to quote something I'd told her my mum had recently said to me at her own wedding a month later, which also happened to be on my birthday. Anyone who licks their lips at the thought of slice of drama pie can do one.
That said, I think I got this really wrong recently. A friend, who I've not known long but have real affection for, lost her baby. I was so conscious of trying to do the right thing I think I simultaneously said too little and did too much. I reservedly offered condolences, made some food for their freezer and invited her for a walk. And at the burial I cried my eyes out, even though it was no loss to me personally at all.
So I guess I'm saying that, when recently bereaved, you have every right to be mad and anyone, frankly. Including those who don't respond to your grief in an appropriate way. But also, you might one day struggle to respond to another's grief in the way you once wish people would respond to you. Which, in a weird way, is proof that grief is both everlasting and something we integrate into our existence and move on from.
I always imagined having had a significant bereavement myself would give me better skills to support others. I've learned recently that this isn't necessarily true.