AITA for telling a woman her child is mentally handicapped after she insulted my autistic son?

Tonight was a very weird night. My son has autism, he is moderately functioning. He is really fixated on food and is a very picky eater (I know this isn't an autism thing, just a 'kid thing') and we were at a book store tonight because my wife had a book club meeting, I was with him looking for something to do before we went to get dinner.<br><br>He was being a little annoying but not super bad like screaming or hitting or anything. He was pulling on my shirt and saying he was hungry. I scolded him and told him to be quiet. Some lady passed by and said "watch it buddy" after I told him to quiet down. I told her to mind her own business.<br><br>Then my son said "I want food" and I told him we were going to dinner in a little while, I told him to be quiet or we is going straight home. Some lady again spoke up and said "what's wrong with your son, why are you being so mean to him?" I told her my son has autism.<br><br>The lady nearby who said 'watch it buddy' said 'why would you bring him out if he's like that? He's being really annoying' and I told her again to mind her own business but she kept pushing me and I finally lost my patience and said to her "you have no right to talk since you can't control your own daughter, it's obvious she has a mental handicap being so rude"<br><br>The lady got mad but like clockwork, her daughter started screaming and having a full on meltdown and she was shouting at her daughter to stop, it was so bad they had to be escorted out. I was told to leave by the staff as well and when we got outside, the lady who I told off was crying and saying she can't believe I said that about her daughter and left. I feel like maybe I went too far with my response. I get she has a mental handicap but she had no right to talk to me and my son like that.