Whether to do so may be a personal choice. But if you do, get out first; don't do it while you are dependent on the place. Based on your description, finding other work that pays at least as well should not be terribly difficult even in this market (the one caveat being to explain why your pay was so low; there was a recent HN conversation on whether to provide previous pay data and how to appropriately decline to do so, that may be useful). And you don't want to be job hunting while embroiled in such a scenario.
Based on your description, I would expect NOTHING from your current employer. Actions speak louder than words, and this guy's actions have "asshole" written all over them.
