Does divorce occur with the statement: "I forbade myself from interfering with you previously, and I went back on that, but now I will never interfere with you"? This is knowing that the speaker had not forbidden that previously, and the intention was to threaten the other party.

No divorce results from saying, "I forbade myself from interfering with you previously," because there is no word of divorce or intention of it. Nor does it result in a prohibition, as it is merely an informative statement. Assuming it were an act of creation [of a prohibition], it would fall under the category of prohibiting what is lawful.