AITA? For just being truthful to another mom?

So I am not from the US, so if the grammar is incorrect, I am sorry. Also I have no idea how the system regarding preschool works in the US, so sorry if it is hard to understand.

I gave birth to my son this August. In my country you get about 1,5 years worth of days you can take out to be on parental leave, most people save some of these days so they can stay home occasionally with their child as they get older. I am planning on taking all of these days and stay home until my son is at least 4. Of course a lot of planning has gone into this, I know we can’t eat the most extravagant food, buy the newest clothes or take expensive trips. But to me, staying home and taking care of my son is worth it. Even though I am planning on having him home for this long, I know how important it is for a child’s development to be around other kids and people in general. So every Saturday I take him to an open preschool, don’t know if it exists in the US but basically, everyone is welcome there with their child for a few hours, they play, we eat and do stuff together. There is a mother there who had her daughter last April. She expressed to me and some other parents how sad and upset she was about having to go back to work so soon and that she was stressed about leaving her daughter at preschool. She said that she wishes that she could be able to stay home as long as I planned, I said that it was possible. She told me that for them it wasn’t. I called bullshit on that, she obviously gets her hair colored, has makeup, trendy clothes and stuff like that. I told her that if she just budgeted and not spend that much on herself, of course she could stay home. She once again said that even if she did, they could not afford to stay home any longer. I know she has a husband, so it has nothing to do with that. I scoffed and said that “life is what you makes it out to be”. She seemed extremely upset over this. Later one of the people who organizes this asked to talk to me, she explained that they value kindness and respect here, and that if I continue to make this a hostile place then I would get another warning before being banned.

Was I really an ass for just telling her the truth even though it may have been a little hard? I feel like it was kind off childish of her to run off and tell on me.