> 1.) Delete their harassing posts and/or report them.
And you've already seen the comment and it's already affected your emotional state. This is also akin to blocking your ears and saying la la la la la.
It fuels the bully and makes you look like a 5 year old. You don't want to look like a 5 year old.
> 2.) Use the privacy settings so they can't see or interact with me
And that gives them free reign to spread any rumors about you and you can't retaliate or even know what's going on. Nobody likes being the butt of a joke they haven't even heard, but everyone else has.
> 3.) Not use the service if it isn't contributing to my well-being
And throw away 80% of your communication with friends and family. Perfect.
It's hard to opt out of Facebook because it does contribute to your well-being. It's just that pesky 2% of times you use it that are the problem.
Luckily all these problems automagically go away once you and your social group grow up a bit. But during early puberty, bullying has always existed and always will. It looks like a core part of how humans work.