All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
First of all, we ask Allah to facilitate your affairs and reunite you with your husband.
One of the most important things that we recommend you to do is to supplicate Allah as much as possible, because all goodness is in His Hands, and He is Omnipotent. He ordered us to supplicate Him and He promised to answer our supplication. Allah says (what means): {And your Lord says, "Call upon Me; I will respond to you." Indeed, those who disdain My worship will enter Hell [rendered] contemptible.} [Quran 40:60]
Your husband is obliged to spend on you according to his ability. Allah says (what means): {Let a man of wealth spend from his wealth, and he whose provision is restricted - let him spend from what Allah has given him. Allah does not charge a soul except [according to] what He has given it. Allah will bring about, after hardship, ease.} [Quran 65:7]
Also, you have the right upon him that he provides you with housing (accommodation), even by renting it. So we recommend that you and your husband have a mutual understanding and cooperation until the matter of bringing you to reside where he resides is made easy.
The second marriage is permissible in principle on the condition of being just between the two wives. Allah says (what means): {…then marry those that please you of [other] women, two or three or four. But if you fear that you will not be just, then [marry only] one or those your right hand possesses. That is more suitable that you may not incline [to injustice].} [Quran 4:3]
However, someone like your husband, suffering need and poverty, should not marry a second wife. The Shariah conditioned the marriage upon financial ability and ordered the one who is unable to marry to be patient and to keep himself chaste until Allah makes the matter easy for him. Allah says (what means): {But let them who finds not [the means for] marriage abstain [from sexual relations] until Allah enriches them from His bounty.} [Quran 24:33]
Also, it is proven that Ibn Mas'ood narrated that the Prophet said, "O young people, whoever is able to marry should marry…" [Al-Bukhaari and Muslim]
The Prophet conditioned the matter of marriage upon the ability. The ability here means the ability to have sexual intercourse and the expenses of marriage, as stated by Al-Haafith Ibn Hajar .
If this is the case for someone who does not have a wife, so what about someone who already has a wife and wants to marry a second wife? For more benefit, please refer to fatwa 139731.
There is no doubt that it is not wise for your husband to take this course of action (marry a second wife). So we advise you to discuss the matter with him in light of what we mentioned or that you appoint someone who would try to convince him.
Finally, it should be noted that some scholars are of the view that it is better to marry only one wife unless there is a need (for marrying more than one wife).
Ash-Shirbeeni, from the Shaafi'i School of jurisprudence, said in Mughni Al-Muhtaaj, "It is a Sunnah that a man does not exceed one wife unless there is an apparent need." Besides, Al-Mardaawi said, "It is also desirable not to exceed one wife if a man keeps himself chaste with her, according to the correct opinion of the School." For more benefit, please refer to fatwa 257272.
Allah knows best.