It seems as though, thus far, you are handling the situation in an appropriate way. You are relying on your father less. That is what you should be doing.
Unfortunately, you cannot force your father to change. You suggested therapy and he said no. You also attempted to explain your feelings to him, to help him to understand your point of view but he did not “hear” you. For him to agree to therapy, and thus begin changing his behavior, he would have to recognize that he has a problem and also be willing to do something about it. It does not seem as though that is going to happen, at least at this time.
Since it is unlikely that your father is going to change his behavior, then you and members of your family are going to have to change your behavior. In essence, the way you interact with him will have to change. For you, it may mean having minimal or no contact with him. This may be difficult, especially because of his controlling nature but it may be the only way to effectively deal with your father.
My recommendation would be to consider therapy. You may want to try individual therapy or with other members of your family. A therapist could gather many more details about your family situation and advise you about how to appropriately alter your behavior when interacting with your father. There is a right way and a wrong way to deal with those who are controlling.
When and if you do change the way you interact with your father, he will likely protest. There is also a good chance that he will attempt to increase his controlling behavior. For these reasons, it is important to have a therapist who can effectively guide you through this difficult process. I hope you consider it. Please take care.