I don't understand

Let me set the scene: a small helpless baby born out of lust and left unwanted to fend for itself in the hospital. A woman barren woman comes along and gives this child everything in the world. Gives it a chance to live and to live beautifully. The child grows and to the womans sheer disbelief spurns everything good that is given to her, takes it and turns it into something wrong. The woman/mother takes it in her stride inside it kills her but as this childs mother *not by blood but every other means possible*  she continues to give her all of her love. When the child becomes an adult age her biological mother finds her and convinces her to come run away and live a life full of sin and deception....the child only wanting to know her "mother" goes with her. To my dismay the adopted mother continues to love and support the child, she prays and supports her. The child begins to self destruct and in the process destroys anything good in her path. The child is now a grown woman somehow stuck in this almost childhood state. Where she is the only person who exists and her drama is all that is important. This child to her adopted families dismay feels the need to glorify and praise her biological mothers life over the family who raised her and gave up so much for her. She is more concerned about her biological mother then the woman who loved her first.  How is this possible? How on earth does it work? How do you say to the woman you loved first who wiped your first tear, who caught you when you tumbled the first time, who saw your first steps and was there for your own childrens birth....how do you turn around and say I love the woman who gave up on me from before she knew me more. HOW