I think because we are introverts our online relationships are sometimes that much stronger than those day to day friendships. It takes me time to really open up to people, and in my experience people are more likely to give you that time online whereas in "real" life they either don't have the time or the patience for whatever reason. To be fair, I think I also feel more free to express myself and less fearful than I do face-to-face, so I know I have met more people (especially on here) that are more similar in their goals in life and personalities because I'm putting true self out more.
I'm sorry about your friend Laura. Death of a friend is never easy to deal with, no matter how long you have known the person. One of my absolute favorite clients (and just person in general) often reminds me grief is a long-term process, so even a year later or more the emotions are still there and deserve respect and care to work through.
Grief is definitely a long term process. I am still not over the loss of my BFF Anna who died traumatically in a car accident in 2003 =(