That's exactly what you feel like when someone (even unknowingly) makes you feel like a bad parent. That happened to me today - someone made me totally feel like a horrible incapable mother. I don't think they meant to hurt me as deeply as they did but unfortunately that doesn't make it sting any less. I know I'm not perfect but I do my best. Not much more I can do than my best except hope that it's good enough.
There are just some things you never forget and this will certainly be one of those.