How Should I Feel?

Just to be clear, I'm not asking my readers to tell me how I should feel, I know, in a way, how I feel, and being told how to feel never helps me at all, because it just makes me want to buck against what I'm being told I should or have to do.
I have a friend on Facebook who I know has lived with a parent who has treated them unfairly.  This parent has said things to me that I don't think were called for.  I have been told, by this person's parent, in a very "righteous tone" that a woman wearing her hair down (in other words, not in a bun) is a harlot.  This person has lived with that and who knows what for their entire life.
Obviously I haven't lived this person's life, but I know enough about their life to know that there have been things in this person's life, maybe even caused by said parent that have, well, to put it bluntly, screwed with them.  I don't know how else to put it.
Messing with someone: That's teasing, maybe a few minor mind games.
Screwing with someone: That's a more painful, thing that isn't easily recovered from.  There is a difference, and while I know some people dislike the term "screwed up" or "screwed with" this is to explain the way my mind sees the difference.
Facebook (I'm still on the same topic, by the way) is a great place.  You can vent, you can talk badly about people, you can talk nicely about people, you can show off your baby, your cat, your boyfriend, so much stuff!!!  But Facebook isn't a therapist, or certified mental health personnel.
I don't know how exactly to say what I'm feeling, deep down in my heart when I see this person post something about how that parent makes them feel, then see people instantly jumping at them for "disrespecting" their parent.  I don't know whether it's disrespect or not.  I don't know what this person was thinking/feeling when they made their post.  And neither does anyone who commented.
To me, reading the post, and the comments that transpired reminded me of when I was in a relationship with a guy who was great at first, but then gradually became...not great.  One minute, I would be angry with him!  SO ANGRY!  But then the next, I'd wonder why I was so mad at him to begin with.
Furthermore, seeing the way this person's parent has treated them, and hearing other things this parent has done/said...I don't think the parent is as righteous as they think.  Fathers are told not to provoke their children to wrath.  I think that also applies to mothers.  Jacob, in the Bible, could have saved himself a lot of trouble had he not listened to his mother.
I'm not sure that this person should have posted the way they did on Facebook, but even if they do/did have problem with disrespect, isn't it good that they're aware of it?  Instead of jumping at them about how they should respect their parent, why not ask why they feel that way?  Sure, yes, mention respect, after all, that is in the Bible, and it is something that a decent human should live by, but the Bible also says that open rebuke is better than secret love (Proverbs 27:5)...does that mean that a person should say when they take issue with someone or something?
When I see these posts on Facebook, I want to help this person, but I don't know how...and I want to defend them...but I don't know how to do that either.  Again, I don't know the attitude they had when they made those posts, and neither does anyone else who read them.
Maybe someday I'll know what I'm supposed to do, and how I'm supposed to feel, but in the meantime, I will be right here, in my little corner, trying my best to shine as much light as I can, and show as much love as I can.  If someone needs convicted, unless I feel like God is telling me to say something, I think I'll just leave that up to him, and in the meantime, I have arms for giving hugs, ears for listening, and a mouth for attempting advice when necessary.
~Katie