No don't do it...don't marry him! Yes Islam does permit a man taking up to four wives but not through adulterous courtships!Heck in Islam adultery carries a death penalty! He is undoubtedly using you & may very well do to you what he did to his first wife! Do you really want to be married to a man you can't trust?Do you really want to live a life of suspicions,unease,& fears? Cut your losses & run girl.. do it while you can!