Mea culpa: "Mey-ah cool-pah". (stressed syllables are in italics) The "e" in "mea" is a short e and should ideally be pronounced the same as in the English word "pet"; but the two syllables in "mea"...
The English equivalent of the Latin phrase 'mea culpa' is 'my blame' or 'my fault'. The opposite is a lack of blame, or fault, which is innocence. And the corresponding antonym in Latin therefore is...