Correct spelling, explanation: threatened is a past simple/past participle form of the verb threaten, which – on the other hand – comes from the noun threat. The correct spelling of this word includes all construction elements: the word-formation basis and two suffixes: -en and -ed. The former creates the verb, the latter is used for conjugation. We cannot omit any of these elements. Therefore, this word shouldn’t be written down as threated. The only correct form is threatened.

Definition of threatened:
verb (past simple, past participle), to be likely to cause harm or damage to something or someone
My knee problem threatened my cycling career.
The scandal threatened to undermine the kingdom.

Collocations with threatened:
Some most commonly used collocations include: threaten with.
They threatened him with expulsion from school.
The man threatened this little boy with a beating.

Incorrect spelling, explanation: this word does not exist in any dictionary, because it lacks one important element: the -en suffix, which is used to form some verbs (like threaten) in English. Be careful not to make this mistake, because the word threated doesn’t make any sense (it consists of a noun and the -ed ending). When we complete this construction with the -en ending, we get the correct version – threatened.