I felt utterly alone and rudderless in the world

I think this encompasses it perfectly. That the world is lesser or harder somehow without.

But it would hit me out of the blue for years. I still dream about them sometimes.

Thanks for your perspective, and this is likely what I fear. It’s weird to know that everyone goes through this at some point in their lives, this sudden feeling of losing the people that made you a child, and now you have to suddenly realise that there’s no one to call upon other than yourself for adulthood