Is divorce effective by a husband's saying to his wife: "Consider yourself, I have absolved you of every need," then his saying to himself in a low voice: "You are divorced," unintentionally?

The phrase you used with your wife is a كناية (allusion/metaphor for divorce). If you did not intend divorce by it, then no divorce occurred. If you did intend divorce, then it has occurred. What happened after the call, if it was merely a thought or self-talk about divorce, then no divorce occurs by it. However, if you uttered the explicit words of divorce, then it has occurred even if you did not intend it, unless you were in a state of bewilderment and unaware of what you were saying, in which case your divorce would not occur.