"Close to a slur" seems like hyperbole to me, but I'm also Team Hispanic since that's just how I've always identified and it's conveniently both gender neutral and widely accepted. I'm personally neutral on Latinx—I'm not offended by it, and it can be a useful indicator for me that someone is at least not a raging bigot, but it sounds clunky IMO and it doesn't work in Spanish (I'd probably go with latine in the latter case).

Regardless, I don't think you did anything wrong, especially since there are absolutely people who self-identify as Latinx. It's just one of those things that depends heavily on your audience.