Christians began to eat pig meat, because the purpose behind the Laws given to Moses by God was to teach people about the nature of who Jesus Christ should be when he came. Jesus Christ fulfilled the law by obeying it and living it. Because he fulfilled it, or covered its entire purpose with his very self being offered as the final sacrifice, we did not need to go by the important attributes of the ordinances given to Moses any longer, but instead of living by what was given to Moses, we rather live by partaking of the holy communion instead, because that is how we commemorate the sacrifice made my Jesus himself.
As for the specific references to this, “Christ is the end of the law” (Romans 10: 4), or “Christ hath redeemed us from the curse of the law” (Galatians 3:13)
You’re talking in circles.
Why did Christians eat pork? Because the Kosher principle—which separated Israel from all other nations by what they ate—was no longer needed—Messiah had come, and was now sending them out to all nations, NOT calling God’s people any longer to be separated in how they ate....
Not to mention Peter was commanded in a vision to eat “unclean” meat of all kinds (as a methaphor and more, for opening the Church to Gentiles). (Acts 10:9-16)
And throughout the Gospels, the principle that food doesn’t defile us, sinful speech does...was a principle Jesus taught, and the Gospel authors interpreted as “calling all food clean.” (see Mark 7:19)