The thing that i kept thinking in my mind..

What should i do if someone that i like so much before comes back when i already have a girlfriend ?

I met that girl when i was form 3. She's awesome and i was so happy being with that girl but we got into a fight and i made a statement that " maybe it's not our fate to be together " . After a while she deleted her facebook and changed her number.

 She just disappeared like dust . I never had a chance to meet her or talk to her. 

But when i'm in form 5 and i already have a girlfriend, she just showed up in front of me . I was like; is this her ? My friend told me that i still have feeling toward her . I think my friend's right but what should i do ? i already have a girlfriend but i still like that girl .. I really don't know what i should do. 

P/s : Guys if you know what i should do please tell and help me .. I really need help now .