I hope you know you're not alone in asking why. I too have asked why many, many times. As I've grown in my recovery I've learned that in many situations there's answer that makes sense. Some of these things happen because of some evil beyond our comprehension and we're left to try and pick up the pieces.
The best possible answer I've found for myself it to try to live my life in a way that takes me beyond that place. If I can help prevent what happened to me from happening to someone else, or if I can give a helping hand to another who has been where I have been I feel I've done my best for myself and others.
Just keep asking the questions and you'll discover answers in places you may not have expected to find them. Just be true to you in the process. Don't sell yourself short because you deserve the very best.
"Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting 'Holy Shit! What a ride!'" ~Hunter S. Thompson