I'm reluctant to do something drastic like cut off contact, which just seems cruel.
He's likely to do that himself, if he's a loyal Witness. When you say it's over, expect to be treated as a pariah. Beyond a mere cold shoulder, if you were to cross paths with him later it would be as though you didn't exist--especially if other Witnesses are present whom he was trying to impress with his "spirituality". Witnesses are expected to avoid "worldly"people unless absolutely necessary. If you break up with him, you become unnecessary.
when we met he was in the process of getting reinstated and kept his JW past a secret. Then when he thought he needed to bring it up, he invented this elaborate lie where a couple JWs knocked on his door and he started studying with them and thought it made sense.
Alarm bells ringing--when else is he not telling the truth? How many more, even bigger, surprises could there be if you stay with him?