I think this too.

One of the things I like least about Facebook, the fact that the people reading your status don't know the thought process behind the post. I guess the wording "at ease" could imply that a different decision/school would make you "uneasy" , a decision some of your FB friends have obviously made iykwim. Of course this isn't what you intended. I'm always careful (or try to be) of my word choice in online communications because there is no "tone" online. By saying instead, "I'm so excited about DD starting school at X school, what a big girl" there is no or less opportunity for misunderstanding.

We all make the best decisions we can for our children but it can be hard when others judge us for them
I disagree. It's the people who took implication from whatever words she used that have to own that. Maybe for her sending her child to the local public school options was an uneasy decision to make, and now that she has made a choice she does feel at ease. In the end it has nothing to do with public vs private but what's best for her child. I often find those who go on the defensive pretty quickly have the biggest hang ups about whatever they are being defensive about. It's hard not to take that personally but I've learnt lately that people should not have to be ashamed or uncomfortable about their lives being positive, whether that be materially, financially or otherwise; just because others are not in that position. It's unfair.