All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
It is impermissible for Muslims to refer their disputes to regular courts run by man-made laws except in case of necessity. A divorce or Khul‘ issued by such courts is invalid and does not take effect according to a resolution from the Assembly of Muslim Jurists of America (AMJA), which is cited in Fatwa 240580. But if the husband pronounces the divorce, it takes effect whether the court issued it or not.
We are not sure whether you are still married but separated or whether you are properly divorced. If your marriage is still intact, you are his wife in Islam and it is impermissible for you to abstain from resuming your marriage without a legitimate justification, such as if you fear that he will assault you or the like. However, you should not leave the matter as it is and remain neither divorced nor married. We advise you to quickly correct your situation by either resuming your marriage or getting a divorce.
If your husband has already divorced you and your ‘Iddah (i.e. post-divorce waiting period) has expired, you are considered among his non-Mahram women and it is impermissible for him to take you back in marriage without concluding a new marriage contract.
You know your husband the best; if you anticipate that your future life with him will be for the better or the advantages to staying married, such as raising your child together, are greater, then you are advised to let him take you back. But if you believe that life with him would most likely impossible, then it is better for you to leave him; hopefully, Allaah will give you both new spouses who bring happiness to your hearts. Allaah The Exalted says (what means): {But if they separate [by divorce], Allaah will enrich each [of them] from His abundance. And ever is Allaah Encompassing and Wise.}[Quran 4:130]
Al-Qurtubi commented on this verse saying, “It means, if the spouses do not reconcile and divorce, they should have good expectations of Allaah; He may bless the man with another wife who brings happiness and comfort to his life and the woman with another husband who provides her a better life.”
Allaah Knows best.