When you say you had no "employment agreement" in place, does this mean that there was nothing in writing? Or do you mean that there was no agreement whatsoever regarding relative contributions, time and financial commitments, division of equity, etc.?
If you would like to discuss this matter, feel free to contact me at (805)259-5778. I am an attorney with a computer engineering degree, and I specialize in IP, corporate, and HR related matters and would be willing to discuss the matter with you.
Kenneth Stein, Esq.