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.
First of all, we ask Allaah Almighty to remove your distress and make a way out of your difficulty, and also to set your husband right, guide him to the Straight Path and allow him to repent. We advise you to supplicate for him as much as possible.
Drug use is a great evil, as drugs intoxicate like alcohol and have the same consequences in the Islamic law. Allaah says (what means): {O you who have believed, indeed, intoxicants, gambling, [sacrificing on] stone altars [to other than Allaah], and divining arrows are but defilement from the work of Satan, so avoid it that you may be successful.} [Quran 5:90]
Moreover, Ibn ‘Umar related that the Prophet, sallallaahu ‘alayhi wa sallam, said: “Every intoxicant is wine and every intoxicant is forbidden. He who drinks wine in this world and dies habitually doing so without repenting will not drink it in the Hereafter.” [Muslim]
It is not forbidden for you to go back to your husband regardless of whether he has repented from using drugs, provided it was not the third divorce. However, if he has not repented, then living with him is a great hardship, but if the situation is as you mentioned, that you might not find another husband, and your daughters need their father, then it is alright for you to return to him, and may even be better for you to do so. However, you must renew the contract with your guardian's consent and the presence of witnesses. For more benefit, please refer to Fatwa 82541.
Allaah Knows best.