Go in tears before her and use pigin English to say -
Madam, i beg you
I use God beg u
the wahala go pass me
I beg you. Make you forgive me.
if to say I never marry/get person I wan marry, na you e for be.
But as e come be now, i beg. no vex. my body want am but d wahala go too much for me.
The tears will convince her and she will leave you alone. she go bow say man dey cry for her advances. she go run cos she go feel say this one no go fit satisfy me. - shock treatment of cause.
be straight and direct to her, you should say:
MISS, I THINK YOU ARE REALLY BEAUTIFUL AND I AM FLATTERED BUT I HAVE SOMEONE IN MY LIFE THAT I LOVE DEARLY AND, IF YOU PUT YOURSELF IN HER SHOES, I AM SURE YOU WOULDNT WANT ME TO DO YOU LIKE THAT.
ALSO I THINK YOU ARE A GREAT FRIEND AND I WANT TO KEEP IT THAT WAY SO PLEASE LETS LEAVE IT AT THAT.