I like my black girlfriend but........?

so i am an east asian dude with a big penis (rare but true), its been measured at 9 inches with a 2.2inch girth, its unusual but true, i got out with this half black girl and everytime i have sex with her she screams before she orgasims and punches me really damn hard anywhere even in my face, if i stop doing her she get furious so i carry on while she beats me, she goes on screaming and orgasiming for well over 5 min, i once got a black eye and bruises on my back where she grabbed me with her theighs and shin and pounded me with her ankles, what do I do? is this normal? and why does she gets like that?