Payment & Deliveries

Sir/Madam I am a prop of small software company which engage is a website development contract with one Businessman. The Firm Owner did not issued any work order and randomly started increasing the scope of work without freezing cost of the development . The relation started becoming worse with time and this month he even went on abusing me verbally and loudly in my office and asked me to close the contract . Today he created pressure on me by calling on father and putting an allegation that i have accepted a particular sum of money and now i am not delivering the project . Sir , in this two years of business relation with this man i have been personally under deep pressure due to his threatening calls.Secondly there is no signed agreement between us which can justify the payments . My father is asking me settle this matter peacefully as i hail from a middle class family and i am startup . Should i start the project ? If yes , how can protect my rights legally . Also how can i claim my pending payments