what should i do?

hi can you tell me whether or not i am being stupid.

2and a half yrs ago i met a man who was very recently separated. i took it very easy and didn`t expect much. from that time to this i have grown to love him deeply. we share a daughter now. however he still isnt divorced and to make matters worse he has lied to me about details to do with the ongoing divorce. i know i can get a bit carried away and tend to blow hot and cold about things but i think that is because i am confused. if he loves me why does he lie to me about things. i have explained that he is risking any future relationship over a past one and that we will split if he lies. he accepts that but after a few weeks i find something new out about him. why cant i find the courage just to walk away?