Have you got any relieving letter, if yes what is stated as 'reason for leaving' ?
It appears they have made out a strong case against you by obtaining complaints from your colleagues, may be as 'you were demanding' money' sort of such things. I doubt very much you will have enough documents & evidences, above all witnesses in defence to support your innocence. Much would depend on these things as a preparatory strategy to decide your next course of action. Methinks, keeping this fight on one side you should pay more attention to your career and settling for your future ventures. That could be even sound like a contemporary or a competitor to the just finished role. May be a start up, a fresh all by yourself or partnering with like minded friends/colleagues. Should be positive, especially you said you established that co. from the beginning. Is't not possible to build your own co. Nothing is impossible, that too in a known field. Honesty is a rare, expensive gift. Don't expect it from cheap and selfish people. Consider this as a God given opportunity to excel. " When you challenge people you will lose one day, when you challenge yourself you'll win everyday" . All the very best for a bright future.