O.k. how do i break up with my G.F.?

Ok im a 12 yearold boi. I date older girls and the older girlz LOVE me. But right now i am dating a 16 yearold. She want's to go.....well she want's me to get a condom. But i wanted to break up with her before she said that. And now if i break up with her i think she will think that i broke up with her becouse she want's 4th base. Im all for it but should i break up before or after we go to 4th and how can i break up with her in a good way?