Is there any Sharia consequence to saying "my wife is unlawful to me" or "divorce be upon me" to oneself, without uttering it, with the intention of obligating oneself to something or refraining from it?

Divorce and prohibition do not occur by mere intention or self-talk without an audible utterance. If the husband does not pronounce divorce or prohibition with a voice he can hear, his divorce or prohibition is not considered to have taken effect. It appears that the whole matter is merely whisperings that should be disregarded.