Kate Nash hasn’t left the angst of her teenage years behind. Instead she’s sharpened her attacks upon social cruelty and treacherous romance, using both stilettos and meat cleavers as weapons of choice. My Best Friend Is You surrounds the British singer/songwriter with an array of retro motifs, invoking the catty side of ‘60s girl group pop (“Do-Wah-Doo,” “Early Christmas Present”), the hyperactive gush of early punk (“Take Me to a Higher Plane”) and the tortured introspection of lo-fi rock (“You Were So Far Away”). Bernard Butler’s production matches thumping drums with chunky guitars and string washes, achieving particularly seamless results on the luminous “Paris” and the moody “I’ve Got a Secret.” Against these backdrops, Nash digs deep into her psyche to unleash such corrosive testimonies as “Don’t You Want to Share the Guilt?” and “Pickpocket.” “Mansion Song” — a scathing feminist rant paired with a tribal-beat track — rips into sexual stereotypes with real venom. At the other extreme is “I Hate Seagulls,” a love song of surprising fragility and hope.