AITAH for untying my bikini top at a public pool?

I (22F) live at a pretty nice apartment complex and regularly use the pool to tan and swim. Today I came to lay out and do some homework and to my surprise nobody was here (this was around 10am). For context this pool is pretty big and if I had to guess there’s around 50 reclining pool chairs surrounding the pool.

Well about 15 minutes ago (11:30ish) a lady came with her kids and out of every open spot chose the seats literally right next to me (Annoying but fine). Well I’m on my stomach laying out in my bikini minding my own business and have my bikini top untied so I don’t get tan lines on my back. (Keep in mind my upper parts are NOT showing I’m completely on my stomach and any side boob would be showing whether the straps are tied or not.

Anyways turn my head and smile at this lady as she’s sitting down with her kids and she gives me a disgusted look and starts scolding me for having my top untied infront of her kids. I was pretty taken aback and said “well you could go sit somewhere else if you don’t like it” and she called me an asshole. So am I the asshole for having my top untied in front of her kids?

Edit:

I think some people are confused, my boobs were not showing at all. My top was still on only my back strap was untied.

Also there are many comments about the dangers of tanning, I hear your concerns. I do use sunscreen and go to the dermatologist every year or so. I am aware that skin cancer is dangerous. Laying out in Florida is no different than going on the boat for hours or spending the day at the beach. Also, almost everything in the US causes cancer- from the genetically modified food to the chemicals in our clothes. All I can do is live my life and take precautions when possible.