You have crossed boundaries that you should not have. You are the adult in this situation and you clearly knew she liked you and you liked her. You should have distanced yourself and remained professional.

You should put this right straight away and be professional - speak to your superiors and tell them - put your student before yourself before you abuse her.

It is abuse - abuse of your position and power and you should rectify the situation straight away.

This is a vulnerable young girl and she should be able to have an appropriate relationship with her ADULT teacher in a safe manner. Your position is one of parental - it is abuse full stop.

Report it immediately and remove yourself from you students life before you ruin her life and that of her family.