This may be asking a bit much without a prior saved game before confronting Pagan Min... But...
Anyway to replay that encounter and change your ending? I've seen the alternate choice of letting Pagan live. And to me, while I believed he was trying to trick you and killed him, actually see placing your mothers ashes as a better ending to me.
So for the sake of endings remorse. Any way to go back without replaying the whole game?