How can I forget someone like you

How can I forget you
When the time comes
That when I needed someone
You were there beside me.

How can I forget you
When my world was dark
And full of problems
You were there to light up my life.

Oh how can I forget someone like you
When you made me fall so badly
And then just left me and bid goodbye
That I was so totally hurt.

And now Im forcing myself to forget you
But why can't I do it?
Can you please help me?
Because all I wanted to do is to forget you!