Has anyone ever lost someone over suicide?

Someone I know took their own life, and this person was a huge part of my life. She was only 18, and it’s been more than a year since she passed. My life seems to be torn in two timelines; one before she passed, and one after, which I’m in right now. Sometimes I think of how the new songs that are coming will never be heard by her. Sometimes I wonder if something ever existed before she passed away, like certain shops on the street or at the airport. I can’t seem to talk about her because I have a hard time believing that she’s gone. I don’t even honor her because of that. It hurts too much to even talk about memories associated with her. It sometimes feel like this world isn’t even real, this reality. The worst feeling that drives me crazy is how it could be my fault, and if I’ve done something maybe she wouldn’t have died. Has anyone ever felt this way? How do you cope with complicated grief that involves suicide? Comments are welcome/appreciated.