Thought Exercises in Deciding Whether to Stay in PhD Program or Leave?
Been to similar situation. Here couple of points: 

Decision and Responsibility: You have enough personal reasons to leave. In fact, I'm impressed you figured it out in the first 6 months, which is a good thing. Here is the thing: You need to make a decision, and take the full responsibility for it. Other people in your research group, might have different agendas, and therefore might give you the answer which is good for them. Probably your supervisor spent decades in research and does not get you, or doesn't want you to leave, because he/she spent time and energy in the last couple of months to guide you through your early PhD stage. you see what I'm trying to say here?

Burning Bridges: If you decide to leave, this is your answer to your current situation, and other side effects are out of your hands. They are not your wife/husband that you need to take to your consideration. It is a professional decision you made for yourself. Good thing is, you are a PhD student and not a supervisor to leave number of students and their future behind. 

Interaction To Your Supervisor: First have a meeting with your supervisor, and tell him/her, your decision. Tell him/her sorry for the situation created but you have to do what you have to do.

Interaction With Friends: You can also let others know about this, and wish them best of luck.