Watching someone you love…die? There are no words for how broken that makes a person. It's like waking up from a bad dream only to find out that it's your reality, it's like watching sunlight fade from the sky, like watching death suck the one you love dry, and being powerless to stop it. You may as well try to stop the waves from rolling in, or the sun from rising. In the end, the waves will roll, the sun will set, and death will come. The only thing you have a choice in? How you deal with it when it does.
Time heals. It's slow and it's painful but it works. Talking helps, going out with other people, seeing friends. She'll be like a book you read long ago. If you trust that if it's meant to be then it'll be again, and if it's not you will wake up one day and realize that you hadn't even thought of her once. And then you'll be free.