Did you transfer copyright to them already? This may have been done clearly or in a sneaky way (i.e., via a “click through” license.) If you have already transferred your copyright, you are in a very difficult situation, that is, if you want out of the contract. It may be too late; you may need to consider getting a lawyer.
If you submit the same manuscript to a real publisher, they will probably ask you if you own the copyright on the work and if you have submitted it elsewhere. You need to provide honest answers to these questions if they are asked or you will be in deeper trouble.
