The Bride is a horrible character.

[El Blanco]

Did the Bride ever make herself out to be moral or good or anything?

No. Not once. She never said anything about some type of morality you are bitching about.

And besides, not only did they almost kill her, it was obvious they were going to try and finish the job.

Why was it wrong to kill Vernita Green? Because she had a child? That didn't stop her from almost killing the Bride. Besides, the Bride made it clear she wasn't going to go after the girl.

It was a revenge tale. Plain and simple.