The story Glinda just told proves that people aren't really born wicked. For how can a baby be evil? She was brought into this world and already she was hated by her father. She spent her whole life trying to make him proud, yet it was never enough.
Glinda:
And like every family- they had their secrets.
Lover:
Have another drink, my dark-Eyed beauty
I've got one more night left, here in town
So have another drink of green elixir
And
Elphaba's mother was having an affair and Elphaba is the product of this affair. Although we don't yet know why she is green, it can be assumed it is because of the elixir.
Crying alone, in a way, is worse than dying alone as when you die, you don't know you've died. However when you cry, you are fully aware that you are alone and no one cares about your well being.
Glinda:
And goodness knows
The wicked's lives are lonely
Goodness knows
The wicked die alone
It just shows when you're
In this part, Glinda is thinking of Elphaba's death. They were friends and so the fact that she died alone saddens Glinda as she feels she could have done something or been there with her.