Congratulations on your self awareness. recognizing your issues is the only way to begin to address them. I hope you have or will return to your counseling, and appropriate medications. No solutions were ever found at the bottom of a bottle.
Congratulations and condolences on being made redundant. I hope it opens a great new chapter in your life.
As to your family issues, I know family is important, but FIRST you do you. Once you have your own issues addressed, then be there for your sister with a shoulder to cry on, or be happy for her, which ever is appropriate. Be there for your grandfather, whether he recognizes you or not, be a loving grandson, or a new friend, whichever is appropriate. I'm going to break pattern now.... DON'T be there for your parents! Be there for your mother, and be there for your father. If they are at each others throats, that's on them. I know it's hard, seeing the foundation of your childhood possibly crumbling, but know that it's up to each of them to find their own happiness, with or without each other. And remember, your happiness is only your responsibility. I hope you will be happy. I hope your sister will be happy. I hope your grandfather will be happy. I hope your mother will be happy and I hope your father will be happy.
As for the drink, only you can determine how much of a problem that is. But if you feel it's out of control, bring it up in your counseling, and possibly join a support organization specifically for alchoholism.
Same with the WoW... video game addiction is a real thing... only you can make that honest judgment.
Finally..... a big congratulations on completing your training to become a leader in scouting. It's wonderful that you care to provide support and guidance to the next generation.