My friend got a better grade than me?

It was a math test and we missed the SAME problems # 3 and # 10 so anyway, i got a -2 B and she got a -1 A, so we got the SAME EXACT answers but then teacher graded it wrong. So i told her i HAVE to tell the teacher, maybe she will bring my grade up. Then my friend said NO!! She WONT !!! SHE WILL lower MY GRADE! What kind of BFF are you!? YOu are the worst!!So i said i wont tell, but i REALLY need a better grade and that happened before cause we have an old teacher and when that happens she says OH! My mistake, and would give the person who missed the problem( in this case ,me) a nother point. So my friend is mad, now we are okay, we are BFFs again but i REally want to tell, What should i do?? SHould i tell, or not? What should i do? WHat would YOU do??????