No one needs your consent to have a conversation, and your former employer is free to give his opinion about you the same as anyone else can do so. There are no special rules that restrict employers' ability to communicate (with few exceptions not raised here).
He can contact your new employer, but if he defames you or interferes with your employment he is exposing himself to being sued by you for defamation or tortuous interference with a business relationship. Tell him you provided 2 weeks notice, the provision you mention deals more with the renewal terms than termination. In addition, unless prvided elsewhere, this provision does not create a non-competition agreement.
Does your former employer have a valid reason to contact your employer? Georgia law provides compensation for intentional interference with employment. You will need to consult with an attorney knowledgeable about these claims.
I am providing general information on the law only, and no attorney-client relationship exists by virtue of this exchange. You can not rely upon this as formal legal advice. If you require specific legal advice, you must hire an attorney and then your communications will be protected by attorney-client privilege, and you will have the benefit of an opinion of counsel. Call 770-753-9995 for a free evaluation.
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