don't know how to tell my parents

I'm 17 and I've been dating this guy for a year a half. When we were first together my dad forbid me to see him and grounded me when he's not that type of parent like it was the only time I've ever been grounded. He screamed at me about it for weeks and it's either because my boyfriend is 3 years older than me or it's because he's native. I'm almost 18 I believe that I can make my own decisions now. But what do I do? His race shouldn't matter but my dad is a little racist. He refuses to ever meet him.