It sounds like you may be feeling guilt because you don't think you can share your special friendship with your parents. Yes, this is a difficult situation. At the same time, it is important to sort through your feelings and put your emotions into perspective. There is no reason why you should feel guilty about caring for any individual; the very fact that you both see past colour, past cultural prejudices is commendable. If you feel honest in your friendship and enjoy sharing with each other, you are not doing anything wrong.
It is important for you to realize that it is possible to care for your boyfriend while at the same time love and respect your parents. You can do both.