On the contrary, when they saw that I was entrusted with the gospel to the uncircumcised just as Peter was to the circumcised

(for he who empowered Peter for his apostleship to the circumcised also empowered me for my apostleship to the Gentiles)

Until certain people came from James, he had been eating with the Gentiles. But when they arrived, he stopped doing this and separated himself because he was afraid of those who were pro-circumcision.