‘Float like a butterfly, sting like a bitch.” That’s the motto brand-new “Real Housewives of New York” star Leah McSweeney swore by while filming her first season of the Bravo reality-show franchise, dropping April 2. “Being on the show is like being in your primal state,” McSweeney exclusively told The Post between swings at Tribeca’s Trinity Boxing Club. “It’s like an animal kingdom — we’re all predators and prey.” And while the single mom never actually came to blows with her fellow castmates — Luann de Lesseps, Dorinda Medley, Tinsley Mortimer, Ramona Singer and Sonja Morgan — she admits there was “a hazing process” when she joined the crew last September. “They were like, ‘Whoa, who is this girl?’ I don’t really think they knew that