I have heard my fair share of comments about having more than the alledgedly normal amount of kids, but never anything that rude and vulgar.

TBH, If it were me, then I would have been so livid, I would have wanted to smack her in the chops and the fury would have me typing feverishly with my own brand of nasty. But the beauty about the typing is it is the therapeutic bit. Hitting submit is one step too far.
So before that happens, I would delete all the nasty and just add "Charming", which is my new favourite word for "You make me sick you pile of gutter trash".

#5 was a surprise package for me too. You think you can't cope. You stress like crazy. You suffer the indignant comments and soul piercing stares. None of it matters when you hold that tiny baby in your arms and remember what its all about. Despite all my reservations, I am so very close to my little Harry. Congratulations on your little #5, and I look forward to your posts of pure joy, because I know that in the end, that will be the bits of your day you will remember.