I don't know anything about the industry, but it sounds to me that the email you sent, while harsh, was appropriate. if no-one outside the company would take the position at the rate they offered, you had the right to protest, and protest strongly. and if you've already heard sounds from competitors, you can reasonably expect to find a similar job at an appropriate salary elsewhere. I agree with what's been said: don't work a job you hate or that treats you like nothing just because you feel you must. you clearly have skills and other opportunities. seize them. you don't need to take crap from them.