Who you are angry with is just yourself. For allowing yourself to trust someone with some part of you that was important. Because you believed that for you, just for you, this thing would last... until death that is.
And then you realize it was never the same for the other person. They always lived life knowing the practical - that things change, nothing's permanent; and they treat you that way. Casual. Superficial. Kind. Understanding.
You could be anyone else on the street. You don't matter.
There's no such thing called friends. Only normal, practical people.