I would say "I had not thought of it in that way."

Yo diria "I never had thought in that way" aunque seria mas si quisieras decir "Nunca lo habia pensado de esa manera",si lo quieres mas apegado a como lo pusiste tu podria ser "I hadn't thought in that way"

'I hadn't thought of it like that' is another alternative.

"I haven't thought it in that way" es una buena opción:)