I'm the other woman...

Sarah
Please help me girls! I am seeing a guy who has told me that he has stopped 'seeing' his fiancé but he still lives with her and the two kids and she still wears the ring. He won't tell her about me... I adore him and don't know what I should do. 
***Update*** 
Guys you were all right. Turns out a wedding had been being planned for October! And look at the lovely message I received.