You don’t need to leave your wife for this reason. You may continue to pray to Allah to heal her and reverse her condition. Mind you there is no shortage of men and women who were deemed as infertile miraculously healed and gifted with children.
I would urge you to make Istighfar unceasingly.  The Prophet (peace be upon him) said, “Whoever clings to Istighfaar always, Allah will bring ease for him and appoint for him a way out of difficulties.”

 

In fact, this is the lesson we learn from the story of Prophet Nuh who preached to his people saying: Repent and ask forgiveness of Allah; if you do so, He will send down water pouring from the skies and bless you with wealth and children.
So, seek possible treatments, if available and make lots of Istighfar; if it is Allah’s will for you to have kids, He will grant your wish.
There is no need for you to marry another wife, for as you should know, there is no guarantee you will have children with her.