Overcoming family objections of interracial relationship

I am brought up in a traditional Asian family where I have to follow the "pre-set" path of studying since I was a kid, getting good grades and engage in a white collar profession. Well, conflicts with my family happens when I started to "venture" out after graduated. For example, a conflict that has always been on-going is my involvement in contact sport, even I made it to international level which mum perceives it as bringing shame to the family and had multiple times threaten me with her life or wanted to disown me. Well, things got worse lately especially she found out that I'm dating a black guy who is my coach. I have been dating this guy for two years and we both are really planning a future together. Again, mum threatens me with her life and even dad's life as she claimed that I will cause dad to fall sick or have heart attack/stroke if he ever finds out me dating a black guy. She claims that this guy is poor with no proper profession and black is the lowest status of race in the community and I bring shame to family. There's no way I can talk to mum and she only wants me to leave this guy. I'm being perceived as rebellious, heartless, "low class" by mum. I really love her and want to take care of her but she wont accept us. Now i'm even more worried to let dad knows about it. Both my sisters are also disappointed with me. I really don't know what to do, coz I really don't want leave this guy and I don't wish to hurt my family.