Lady thought my nephew was my son

So I was out shopping with my sister in law and her son and we were in this store and my SIL found some clothes she liked and wanted to try on but didn’t want to take my nephew in with her so I told her to just go ahead and try them on and I’ll watch him so she thanked me in went into the dressing room.

Well I found a chair that was next to the dressing room entrance and told my nephew to come sit on my lap while we wait for his mom. And he took a seat on my lap and I gave him my phone to watch a show on so he wouldn’t start getting fussy about waiting(and being bored) and he ended up throwing his legs over the side of my legs and laying his head next to my neck so he was more comfortable that way while holding my phone(and it was honestly a bit easier to hold him that way too) and since I didn’t want to disturb other people so I took out my AirPods and told him to put them in his ears so he could hear his show better(and he did). Well a few minutes passed and he looked up and started messing with the hood of his jacket and I asked if he wanted it on and he told me he did because his ears were getting cold and that made it uncomfortable for him. So I helped him put it on so that way he wouldn’t knock the pods out of his ears and also since his attention was still on the show and he just went straight back to laying against me after telling me that.

So after he did that this older women was looking at clothes near where he and I were sitting and kept looking over at us so I just gave her a polite smile and she just glared at me instead so I was just okay whatever but then she came over and was like “I see you have a child” and I was like “yes ma’am I do” and she asked how old I was and told her I was 18 and then asked how old my nephew was and I told her he just turned 5 and then she out of what seems like no where starts lecturing me about how people my age are having kids when their still in their young teens and ruining their future because of having a child so young and I should be ashamed of myself because I was so young and instead of focusing on my studies I focused on boys and sex and got myself pregnant and just kept going on and on and very loudly too that I couldn’t even tell her he was just my nephew that then when my nephew looked up at me and told me his show had stopped playing(it was actually only buffering but he didn’t know that) so the lady stopped talking while I told him just to wait a moment and it’ll start up again so he waited and the lady wasn’t finished with me and started saying how my own son doesn’t even call me mommy because I’m old enough to be his sister and I’m frying his brain before he can even learn anything because he’s watching stupid shows on my phone(which he wasn’t watching anything stupid but was watching a show that helps spelling out words and other things like that to help him in school) and I started getting super fed up by her because she saying all of this in front of him and thank God he had the pods and was just focusing on his show because otherwise i don’t know what would of happened because he could of heard all of this and then be confused. But she was just assuming all of these things but also insulting me, my nephew and my SIL I felt like too and before I could talk back to her, my SIL came out and called my name out and asked if I was alright and asked why this lady is practically yelling at me and before I could tell her my precious nephew looks up at his mom and says “Mommy you’re out! Can we go home now?” And the lady just made a confused face at him and I took the moment and calmly said, “He is my nephew and not my son like you just assumed. I would of told you that sooner but you wouldn’t let me speak.” And she was trying to find words to say because she seemed embarrassed and so I look down at my nephew and ask him if he can get off my lap(and he does) and I say to my SIL “Want to go check out the clothes you found so we can head back to the house?” And she said yes but had a confused look on her face but we walked away and the lady still didn’t say anything so we got away from her and then I started to explain what just happened and she felt so sorry for me that I had to just sit there while this random lady lectured me about something that wasn’t even true! This all happened about 20 minutes ago but I’m still so mad because why would she even just assume he was mine when he could of been my little brother, my nephew, another family members kid, my cousin or even a older friend of mines kid! Like what just clicked or rather didn’t click in her head that he could be anything else other than my child?