Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.

 

A Muslim man can only marry a Muslim, Christian or a Jew. Any other marriage outside this is not Halal in Islam. I am not sure of his wife’s religion as you did not mention it.

 

Also, he needs to clear his record from legal marriage from the first if he wants to marry you depending on the rules of each country and regulations.

 

I am also not a favor of describing your relationship with him as being your boyfriend! That means there are some practices that could be Haram going on before a real Islamic marriage took place.

 

In all cases, when he is ready for marrying you, he must come and ask for your hand, with witnesses, with the approval of your father and putting Mahr.

 

Almighty Allah knows best.