You will loose your LPR status if you do not return to the US. Should you intend on staying outside the US I suggest you go to the US Consulate and speak with an officer to retain your status.
Your husband can file charges against you for taking the child outside the country and keeping him outside the country.
If you are only referring to not going back to your husband - you intend to be in the USA - you do not have an immigration problem but you may want to speak with a family law attorney.
I agree with my colleague.
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If you do not return to the US, you will lose your permanent residence.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.