Why dont my parents let me date a black (its long)?

im a 17 year old white boy whos cuban, and had gotten real close to this girl, shes black and we instantly hit it off. we have so much chemistry i had the hugest crush on her shes super cute and smart. i told my dad back in november i had been getting close to her (he works at the school and knows her) my mom overheard and asked me what ethnicity is she and i said black and she flipped out! i had no idea she'd react like that and never have i gotten any hint they wouldnt approve of me dating a black person. i got really mad and my dad told her to let me date her because i was just going through a "phase" -__- anyway since november we've been dating but its been kinda hard to see her because she lives far and shes not allowed to do anything with my family and it has been making me super depressed. our relationship has only gotten stronger and recently they both Ganged up on me and kinda forced me to break up with her. my mom told me she cries every night and my dad says he doesnt want to deal with it. then they say im not respecting them and i should respect what they say, they give me all these reasons why i have to break up. i dont get it. my dad knows her and knows shes a nice girl and she gets good grades and no shes not ghetto. but he still doesnt let me? my mom says its jsut because shes black she can give me no other reasons. they say im a bad example to my 3 younger siblings just because of this. (i get good grades and am never in trouble, but im a bad example?) my sister met her and she likes her for me. but my 7 year old brother is like completely discouraged from blacks now because the way my parents act. anyway so just like 2 weeks ago they took away my phone, my ps3, and computer unless i break up with her. so i agreed after about 5 days and got my stuff back, but idk what to do now. i told my girlfriend that we have to "pretend" that were just best friends for now. but it is just so annoying to me and makes me so sad. she cried too. i wish i can have her 100%. i REALLY like this girl, i love her. our relationship is awesome its the best one ive been in (outside from the parental issues) =( this sucks because i have a pretty good relationship with my parents but this has torn us apart, but now since i "agreed" to break up theyre getting friendly again. ive tried talking to them about everything they just dont care about anything, just that shes black we have to break up. what about later on in my life? are they gonna send me flaming poop on my doorstep? cut off communication from me? probably, cuz i dont plan on stopping with this girl. why do they have to be like this its really no big deal to me, or anyone else, only my parents