I ate squid ink pasta and, sure enough, the area around my mouth turned black.
イカ墨 = squid ink
パスタ = pasta
食べる = eat
て = and
案の定 = sure enough
口の周り = the area around my mouth
黒 = black
なりました = became -> turned*
*色がかわるとき「turn」をよく使われています。
My arm turned black and blue.
「案の定」はほかの言い方もあります。
as expected
wouldn't you know it
as I thought (it would)