What if professional relation mixes with personal and effect badly?

This man proposed me before 4 years, he is married for 13years and have two kids. He never tried to take advantage of me but helped me in many circumstances. After 4 years he has same feelings for me. He proposed me to marry him but I denied. Later on I fall in love with him, and gradually my feelings become strong for him. We made love and he involved me with his business and I represent a institute with his help, before few month everything was going well but when I asked for marriage suddenly he got scared and asked me to wait for right time to come. I understood about his feelings for me was not true. But he is not bad at heart too. My question is I know I cant marry him neither cant leave him bcoz I want to establish and expand this institute that I represent. He is there for me proffesionally but he try to get physical with me. He does becoz he think I have no way to deny his proposal but have to accept it bcoz he is financially and socially very strong. But I am trying to avoid this and have stop taking help financially from him for the institute. And run by my own money. But he has many network suppport and any how I have to be depend on him and I cant even quit this business. What shall I do so that he and my business dont get mix up and I gt escape from him personally. I am not married and single. Pls help.