I just want to put it out there that “bless your heart” doesn’t mean “fuck you”. It’s a catch-all phrase that can (realistically) mean anything you want it to, but it’s mostly used as a substitute for “no offense”.
"Bless his heart, he ain’t got the sense God gave a gopher."
All my life I’ve heard and used it for everything from “the poor, dumb bastard” to “I am so terribly sorry but at the same time am very glad that it’s not me” and even so far as a genuine “you poor darlin’!” (I’m from the backasswoods of Georgia- we use it like fucking punctuation). But I’ve never known that anyone who uses it in the capacity of “fuck you.”
If you’ve made us mad enough to think it, we’re just gonna say it. No sugar-coating.