One can understand your love for your cousin after all that he has done for you. In the perceived absence or lack of love from the parents, any gesture akin to love can be very comforting and consequently valuable. Therefore, it is not difficult to understand that you do not want to let go of this relationship.
However, the one thing that I would like to remind you of is that life is not just about one relationship. There is a lot more to life and a lot more that you need to do for yourself. At your age it becomes even more important that one does not overlook the other aspects of life. My advice to you would be to give this whole thing a little more time and use this time to fulfil the other dreams that you have. At the end of it all, its your life and obviously you decide.