I doubt he would win a lawsuit unless it is specified in your contract. Since the reimbursements are associated with your tax identifier/NPI, it is to your benefit to retain a nonregistered (for EHR incentive) status. That way, if you start your own practice with EHR, you would maximize your reimbursement. Or, if you join another group, you could try to negotiate EHR reimbursement.
If you are leaving, you need to carefully review your contract. Have a good exit strategy and hire a lawyer now. If there is already bad blood, the departure will not go smoothly. The sticking points will be (1) who pays tail coverage for claims based malpractice (2) non-compete if you stay in the area (3) informing your patients of your departure (4) getting paid.
Document everything.