Have i become 'the other woman'?

He's leading you on. Just give him an ultimatum: Leave his wife immediately or you walk. Plain and simple. If he REALLY cared about you and meant what he said about leaving his wife then he would do it. He's just delaying cuz he knows your feelings for him will grow stronger until you just dont care that youre the other woman. Respect yourself and dump the guy unless he settles to your terms.