that was long. but after reading all you wrote I see that that not the right girl for you. you are too sensitive and kind and she likes to flirt, lie, be dishonest... she doesn't see you as a couple so maybe you shouldn't too.
If you still wants her, you need to give her an ultimatum, be with you or go to the other guy.
I personally think she is not good for you and many girls will stand in line to be with you, she just not worth it.
good lack.