、。
The instant she heard the news, she suddenly burst into tears.
Literal
She [topic-は] that news [object-を] heard [the-instant-とたん], suddenly burst-out-crying.
~たとたん(に) ('the instant, the moment') marks an immediate, almost simultaneous reaction — what happened just as the prior action completed. Stronger and more abrupt than ~とすぐに ('as soon as'). The construction takes the past tense (聞いた) before とたん, then the resulting action follows in plain past. Pairing with 突然 ('suddenly') is mildly redundant — both elements stress immediacy — but the doubling drives home the abruptness of the eruption.