Defaming by x-employer

I was in service for last 14 years in an IT company. last 3 months i got another job contract-full time with another IT company.I started the job with new organisation w/o disclosing to either of the employers. after a week i got up in a call with a new employee who was a friend of my manager in old Organisation. i had to disclose everything to my old organisation. we agreed that i will resign with immediate effect from the old org and pay for my notice period in return, the old org will keep the matter confidential and give me a clean exit with no impact on my new job. But this did not happen: after few days i was told by some existing employees that an email by Country Manger has been sent about an employee with 14 yers who was involved in moonlighting and had to b departed.this email did not directly mention me, but in verbal clarification to few employees, it was confirmed that the email refers to me. Further, there was an email to my new org CEO from the old org CEO about a breach of contract by me. I ned to explore my legal option in this case.I have not talked to anyone in org about this since my ful and final settlement is still pending, including the gratuity amount.