So I checked the flowchart for NTR/Cheating ruling, and I would say it is ntr, but it isn't for cheating. Since party C, Widowmaker, is shown to only have interest in making party B, Tracer, into a sex-slave through coercion through blackmail. While the same can't be easily said for party A, Emily, given her reaction it's fair to assume the same tactic was used on her.