My employer got angry with me for not dropping a request for back pay, then said they would make a case that i altered emails from Sept 2013 that said I would get retro pay. He offered me a raise, in writing and offered me benefits, then took it away when i refused to drop the back pay issue. is he allowed to do that?

It is not so much a question of whether he is allowed to do it. The real question is what can be done about it. The only thing that can be done is to leave and start a claim against the company for constructive dismissal. You should never leave without speaking to us first. If that is something you would consider doing, please give us a call to discuss, at the number below.