Creating a compnay that competes with your current employer while you are still employed (talking to potential clients and not offering those clients to your current firm is starting your business) can itself lead to a lawsuit. You can be sued at anytime for almost anything. If you want to make sure that you bild the most defensible case don't do anything to get clients or create your business until you quit. Don't go to any of the prvious clients of your ol firm for at least three years and do not use any knowledge that you gained while with your current employer that is not in the public domain.
Are any of you subject to any restrictive covenants or other non-compete agreements?
The act of meeting together and seeking out new business for your yet to be established company may be a breach of the duty of loyalty, tortious interference with contracts and tortious interference with prospective business advantage. Depending on what kind of information you might be taking with you when you leave, you may also be violating confidentiality and trade secret provisions.
I would be happy to meet with you and your colleagues to discuss what you have done and what you plan to do to avoid/minimize any risk of litigation or threatened litigation as you embark on your new venture.
Neil S. Hyman, Esquire
Law Office of Neil S. Hyman, LLC
4416 East West Highway, Suite 400
Bethesda, Maryland 20814
Licensed in DC & MD
It sounds like you may have already gone too far down the road of breaching your fiduciary duties to your employer. Contacting prospective clients on behalf of the new business is a violation. The only sure ways to avoid being sued would be to stop what you are doing now, before the employer suffers actual damages. Also - note that if you drop out of the civil conspiracy, and the others continue, you could still be liable.