The 48-year-old discussed Singer's comments about Shields, Frankel's late boyfriend, during Wednesday's episode of "Watch What Happens Live."
"It was in really poor taste. It was actually fairly despicable -- that would be a pretty bad word," Frankel told host Andy Cohen.
"People have come up to me and said that over the course of the last 10 years she's done some pretty nasty things, but that was by far the worst," she said of Singer, her "The Real Housewives of New York City" co-star.
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