OP: By the by it would be seriously negligent of me NOT to advise you about the Emails, and you serious PERSONAL LIABILITY.
Unless the terms to the termination of your employment agreement were amended, noted, or inclusive of a EXCEPTION, those contacts and emails were, are and always will be the PROPERTY of your ex-employer, just as much as if (in the court's eyes) you took your office furniture, put it into the company van and drove both home (THEFT) without permission of your ex-employer. Typically the use of the contact/email in any way can be grounds for Federal Charges of Theft, Insider TRADING, Proprietary information, Corporate Espionage; all with FEDERAL jail time. The 'least' would be the ex-employer lawyer sues you for Breach of Contract, Misrepresentation for the purpose of Fraud, Breach of NDA, Breach of NON-COMPETE clauses, etc. which TYPICALLY are $100,000 or the value of the loss (unlimited $ as noted in the DCMA song pirating lawsuits or Hacker lawsuits for $100M, etc.) PLUS ex-employee Civil, Legal, and Lawyer Costs.
If your terms of termination had you agree that you provided back all assets to the ex-employee, that includes ALL those emails and contacts, etc. The ONLY exception that protects you from MOST (not all) of this (you can still be personally liable - SIGH!!) is WhistleBlower protection law, but as noted you can still be sued and court order pay back for 'damages incurred by plaintiff' even if it was a Whistleblowing they poisoned and killed 100,000 people knowing, etc.