Just need to hope business lets me go early.
do you have any vacation time you can take ?
in my opinion threatening people in writing just puts people on the defensive. i feel it would be better requesting an interview with someone higher than the lady you have issue with and explain you feel badly treated, you have another offer and you just want to go and walk away with no hard feelings (or as best as you can muster)
i just think making threats to people, even if justified, will have an equal and opposite reaction
good luck mate