Is a divorce effected by the words, "By God, if you don't stop, this will be your last night in it," or "I will make this your last night in it," with the intention of threat and not divorce?

It appears from what has been mentioned that this is merely a promise and a threat. A promise is not considered a divorce unless the husband pronounces it. Also, the phrase mentioned is one of the allusions (kinayat), and the words of allusions do not effect a divorce unless there is an intention (qasd) to do so, and there is no such intention here. Based on this, the wife remains within the marriage bond. Caution must be exercised with divorce pronouncements, both explicit and allusive. If you do not fulfill what you swore upon from what you promised, then an expiation for breaking an oath (kaffarat yamin) is incumbent upon you.