Ouch, ouch, ouuuch !!!!!!!!!
Oh you poor poor girl... if you cannot see what this man is doing. Oh my my girl.... the guy is using you to get his wife and child into the country and as his bank account. You won't get the money back. Don't give him any more, make excuses why you can't, but please don't give him anymore.
Oh I wish I could get to you and shake some sense into your head.
Once his wife and child are over here you will not see him unless he needs more money. He may even say that they need to live with you for the sake of the child because he can't find a home for them.
Your situation isn't unique, it is happening to a lot of men and women all over the world.
Get rid of this guy, and then change your signature and bank account number anything that he may be able to access.