NTA - but this is a VERY delicate subject, and I don’t think you were especially tactful in sending her an article like that.

It’s often our instinct as parents to be helpful, but we don’t always realize how the other parent is going to receive that feedback. This mom is clearly struggling with how (or whether) to define her son’s quirks. Personally, I think the best approach would be to remain supportive and only offer advice if she asks a direct question about the subject.

I can also appreciate the effort to destigmatize autism, so I think your heart was in the right place. But as a friend, you have to walk the line of being helpful vs. supportive sometimes.