@batman21 Don’t fear, you were right to refuse! People like this can really make us doubt ourselves, or leave us with heavy feelings hanging over us. (Apologies for my odd speech, I have autism)
I can assure you that I have never met anyone (at least in this century) who would let their child ride without a car seat, much less encourage another parent not to use one. Your gut feeling was absolutely right, it isn’t safe.
I wonder if some of the emotional discomfort this left you with has to do with someone whose friendship you value, someone you may trust, behaving in a way that is hard to reconcile with that.
I don’t know your friend, so although her stance on car seats is bafflingly dangerous, I don’t think this necessarily makes your friend an all-around terrible person or mom. We don’t always know why people make grievous errors in judgment, and we are not bad people for having compassion for our friends. But it may be worth checking in if you feel this behavior is highly unusual for her, as recklessness and uncharacteristic behavior might indicate she needs help with, say, a mental health issue, or domestic problems.
Good on you for standing your ground. It’s not easy, but it means you’re willing to stand up for your kid, and that makes you a great parent in my eyes.
I hope you feel better soon.
Edited to add: Having said all of the above, her habit of picking apart your parenting definitely is not cool—I for one always feel awful if I think someone thinks I’m a bad mom—and you can absolutely tell her that it’s hurtful and needs to stop.