Can my lawyer represent me and someone against me in the same case?

A man wanted me to take custody of his wife we hired a lawyer and gained custody of the woman. (These are elderly people, in bad health). After gaining custody the man decided i wasn''t doing as he wished. However, I was trying to do what was best for the woman. The man then hired my lawyer to represent him and another individual to take custody from me and give to the other person. Can my lawyer do that? He also represented me in a different legal matter which I also am having difficulty with.