First off it would be best to quit Runescape. It seems it's a factor in bringing you down.
You need to overcome your fear of social interaction. You can work on that slowly one step at a time.
Take a break from video games honestly, it seems like it's negatively affecting you.
Try participating in public events more often when you get the chance, maybe head to a local community centre once in a while, who knows you might make some new friends plus it couldn't hurt.