Rahjah
To me it sounds like they are the ones being judgemental of your parenting.

From their side of the fence, they probably feel exactly the same way as you do (well they obviusly do as they said it to you), and would therefore feel just as judged. As above, we're all doing whats right for us.

I think the only situation in which I think I would not be able to restrain myself from intervening is if I felt they were doing something that was putting the childs safety at risk.

I do find that it matter what aspect of how we parents DS it is, theres someone who questions it, tells me its wrong etc. And I always think to myself ' think what you like, but why the need to tell me?'. They know they wont change my mind.

You dont have to sit through their choices if you dont want to, though it may mean losing that friendship. Do you want to keep it? It comes down to whats important to you.