Why did Mohini let Rakhi killed?

After seeing the revelation episode, I am wondering what is the idea behind killing of Rakhi? After all she is her daughter.

raaste se hataya she said... so may be Rakhi would have witnessed something with which she might have understood Mohini's true color...

Yup...I also still didn't get it..killing your own daughter..????..I think it's too much..too heartless..even Rakhi was not her real daughter ..it's totally insane by killing her...Why Ekta had to come up with the idea mother killed her own daughter..?? I am  a mother..I couldn't tolerate such kind of story..😡😡

all ekta shows start out great but soon become total junk. KB is another good example.