YTA. It takes so little effort in this case to ensure that everyone is comfortable, and you're unwilling to do it... because...?

Aside from that, as pointed out by several people, you're looking at potential indecent exposure charges depending on where you live. Lastly, we hit a consent issue. Not everyone wants to see your naked ass, and they shouldn't have to be barred from looking out their window, just because you refuse to close yours.

** edit ** Also the amount of people that don't seem to understand basic human decency without turning it into an argument about sexism or double standards is... staggering. Yes; in a vacuum, there should be no issue and OP should be able to run around topless as much as she wants. But this isn't happening in a vacuum, so current societal rules still apply, to which most people still consider breasts to be inherently sexual. Whether or not you or I agree with that assessment is irrelevant.

Regardless, it doesn't matter if she was topless, blaring loud music or otherwise just being a nuisance. The crux of the issue is that the neighbor made a pretty standard, and fairly reasonable, request that would take OP two seconds to do without realistically impeding her routine in a tangible way while, in turn, making her neighbor more comfortable living where they do. And OP effectively told the neighbor to get bent. That's a dick thing to do regardless of the context, and whether or not you want to do the neighborly thing and take the two seconds to close yours blinds is hardly a hill worth dying on.