Struggling with me

Hey guys, I recently got into it with my mother and she said something to me that I’m not sure if I should be angry about or just let go.

I am 29. I was adopted when I was 8 months old. Growing up I was told that I was Japanese and Pacific Islander (Samoan/Hawaiian). I have always been told I look Samoan because I honestly do. And my mom would always say the reason I’m in the bigger side is because of my Samoan genes. She would constantly comment about my weight growing up saying if I didn’t eat better I would activate my diabetes because it’s common for Samoans. I recently did a 23andMe test and found out that I’m Japanese, black, and Native American. Nothing else. I was shocked. My mom didn’t want me to do the test in the first place and told me I was opening a can of worms. When I told her she didn’t have much to say and didn’t want to get involved. I found out I have a half sister. Has never asked me how I felt about anything regarding my adoption, finding out my real ethnicity, finding out I have a sister. No interest. My dad is very very supportive. I got into it with my mother and she told me in a very condescending and belittling way “ to be honest, I knew you were black when we got you. I just never said anything” idk why but that really cut me. It felt violating. My adoptive mother is Japanese and my adoptive father is German. I have always felt growing up that they were a little prejudice against me dating black guys when I was in my teens. My mom always use to say that I was so ghetto, or I act ghetto, or act black. Feel like she hid if from me because she didn’t want to believe that I was black or idk. She never talks to me and we have never had a good relationship/ mother bond.  But idk if I’m over reacting and I’m just emotional and shocked about finding out my real ethnicity and everything else. Maybe it isn’t that big of a deal but I just have felt lost since I found out and just feel like the only people I can really talk to about it is my parents. It has always been just us 3.