Take another look at the sentence:
The sentence requires the simple past of tear, an irregular verb. Tore is the simple past form.
|Verb||Simple Present||Simple Past||Past Participle|
Had torn, the form you chose, is the past perfect tense. You only use this tense if you have two verbs in the sentence, one indicating an action that comes before the other. Before you continue, review the rules for irregular verbs.