What Pusha T is to cocaine crime sagas, what Cash Cobain is to lustful odes to women with donks, SZA is to gut-wrenchingly realistic stories of ungrateful, cheating, boneheaded exes so self-involved they don’t even realize they’re the supervillains. I think of the dude on “Kill Bill,” having a jolly day at the farmers’ market with his new girl while SZA is ready to take Death Wish levels of revenge on his ass. (I get it; giddily buying a fresh bunch of cilantro while having a burned ex out