|What you are really saying is that unless you go against what you think is right, ethical, and fair, you will lose the new job opportunity. In this type of situation, there are compelling arguments on both sides, and you need to make a decision that will not keep you awake at night.|
On the one hand, in the cold world of business, you are most likely an "at will" employee, and this means that your employer can let you go pretty much at its own will, provided it does so within the law. And, some would argue, as long as you can be let go at the drop of a hat, you can do likewise to the employer. And further, some employers take the position that when an employee gives notice, he or she should leave at once.
At the same time, if you simply quit, you are failing to complete an obligation that is important to you, and you may be burning a bridge. You might be so distressed by doing so that you can actually resent your new employer and hinder your own performance and success before you even start.
A great deal will depend on the working relationship with your present employer, and the actual opportunity being offered by the potential employer. However, something deep within you is saying that you should not just hit the road. That voice is always worth hearing.