The reason they open their mouths is to accuse the writer. Alternate translation: "They shout at me in order to accuse me" (See: [[rc://en/ta/man/translate/figs-explicit]])
This is an exclamation that is used when something is suddenly seen or understood. It emphasizes the statement that follows. (See: [[rc://en/ta/man/translate/figs-exclamations]])
Here "our eyes" refers to the enemies' eyes. It is implied that they are saying they saw the writer do something wrong. Alternate translation: "we have seen it" or "we saw the wrong things that you did" (See: [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-explicit]])