My (29M, Nupe) parents are threatening to disown me if I marry my girlfriend (27F, Yoruba) of 9 years.

I’m completely shattered right now and need some brutal honesty from people who have been through this. My girlfriend (27F) and I (29M) have been together for 9 years. We met in uni, grew up together, and have built an amazing life. She is my absolute rock, and our relationship is incredibly healthy and loving.The issue is ethnic differences. I am Nupe and she is Yoruba. For years, my parents basically ignored the relationship, probably hoping it was a campus phase that would just fizzle out. But now that we are actively planning for marriage and looking at houses, my parents have completely flipped out.They sat me down for an intervention and told me that marrying her would "ruin our lineage," disrespect our traditions, and ruin things for future kids. They are using heavy emotional blackmail, tears, and flat-out threatening to disown and cut me off if I don’t end it right now.I love my family, but the thought of dumping a beautiful, 9-year relationship to appease tribal sentiments feels totally wrong. If I leave her for them, I know I'll resent my parents forever. We are both financially independent, but the emotional guilt is suffocating.Has anyone else dealt with this specific Nupe/Yoruba dynamic, or general tribal rejection? Did your parents ever come around once you stood your ground, or did you have to walk away for good?TL;DR: My Nupe parents are threatening to disown me if I don't break up with my Yoruba girlfriend (27F) of 9 years. We are independent, but the guilt is killing me. How do I navigate this?