I think that putting much emphasis on being or doing "good" is a set up for feeling bad at others when they fail to live up to your standards or when you are not rewarded for being "good." I don't think "good" is something that can be rewarded by others - if for no other reason than I don't think everyone agrees on what "good" is.
I did not read the thread as your "healthy boundaries" being the difficulty others found with the posts. I read everyone as supporting your boundary setting as a good thing. I found the challenge to be where it seemed you set good boundaries (a positive thing I think) and that was not enough - you were still looking for some sort of affirmation or sign or acknowledgment of your email pointing out her flaws (which I am in no way saying do not indeed sound flawed) from the woman you set the boundaries against.
I do think the boundary setting thing is a positive and healthy step. I think expecting the other woman to react in a positive or penitent fashion after having her transgressions emailed to her regardless of your intent that she take the email to heart and use it to change her shiftless ways, may have been a bit of an overly ambitious expectation.