Guilty feeling. Guilty and want to die.

I am 21 yr old male.i was 14 or 15 when I was sexually attracted towards my sister who was 14.i would touch her inappropriately .I would touch her body inside the dress.i did that a few times and stopped later.but suddenly I did that after 2 or 3 years once or twice when we had to share the same bed.i have immense respect and love for my sister.but I do not know why I did that because when I stopped ,I again did that once when I was 17 or 18 .but I feel extremely guilty now and want to die.i am not able to face her though she is completely unaware of this and is Normal around me.i feel extremely guilty because of what I had done in teen age.now for the past 3 years I have become matured.pls help me as I feel extremely guilty and want to die..