I don't love my girlfriend anymore but I don't think I could ever dump her.
What is it that makes you think you could never dump your girlfriend?
I have a lot invested in her. For instance I have bought a house together. In addition, she supports me emotionally.
Even if you are entangled with your girlfriend in many ways, it would be kinder to break up if you don't love her. Using her for emotional support and entangling your finances together isn't fair to her if you don't want to be with her.
Breaking up with her is easier said than done. I'm scared of being single.
It sounds like the love for your gf has faded and since that is the case trying to hang on for your own purposes would be wrong. Do what needs to be done and let her go, even if you have to deal with your own loneliness and emotional dependencies for a time.