It sounds like you are just so unhappy in this relationship and it doesn't seem like something you want for the rest of your life. Maybe you should have a talk with him and tell him exactly where you stand and what you dislike about the relationship. His reaction would be very insightful and maybe help you to make a good decision about what you want to do. He seems like he could have the potential to become abusive (very needy, keeping you from friends and family, keeping tabs on you at work) and if that is the case you want to be out of that relationship as quickly as possible and never look back. The fact that you work with him and that you have to work there for the next few months makes this situation so much harder, but I know that you are capable of doing whatever needs to be done. You are probably so much stronger than you give yourself credit for. You deserve a full and happy life...just make sure you are with a guy who can give you that. If you are happier being single, then maybe you should think about going that direction with your life. At least for now.
Good luck and we are here if you ever need to vent. We all need an outlet every once in a while.
