How can one repent from talking to a strange man without her husband's knowledge, and will Allah forgive this sin even if it was limited to just talking?

Repentance from any sin involves abandoning it, regretting having committed it, and resolving not to return to it in the future. Thus, repentance from speaking with men – in impermissible ways – involves abandoning such conversations, regretting what has passed, and resolving not to return to it in the future. And whoever repents with sincere repentance, their repentance is accepted – Allah willing – and they become, concerning this sin, like one who has not sinned; for the Prophet, peace and blessings be upon him, said: "The one who repents from sin is like one who has no sin."