I think you can't blame yourself for other people choices. Can you know for sure why your parents are still together? How can you say it was because of you. It is their decision, their life.
Anything of that is not your fault, trully, and if they stay together because of you, it means one thing, that they love you, they care about you and they want you to be in their life...they realy wanted a child, so you're meant to be here.
You're life-dead experience is a very strong one, and it can certanly change the way you see life. But once again you survived. How can you know if a person in that situation that instead of you died would not feel the same way during the fall. People barely think about dying until they see the dead in front of their eyes. You had a terrible experience that made you wonder about your life.
And finaly you can't resume your love to a girl that is know far away. I let go all the guys I ever liked. I thought about them for a long time after they were gone. But who knows what life will bring, how do you know you will not meet anyone else special as well, how do you know that you will not see that girl again?
Yes, that's a lot of things to contaminate you're mind. But in my opinion they are nothing you should be ashamed of. If you fill you need to speak to someone, someone you trust, I don't see a reason to not do that. Perhaps it will help you to let these gosts free.
I think you deserve to be here!