ArtFriend, as you see you have lots of support and friends here. We are family and we do understand how hard this is.
I'm sorry for the losses of your sister and your mother, but I suspect they would both want to see you living your life to the fullest. Your sister loved you and took you to art galleries to help you develop your talent. Now you can pursue your art, which your sister would love to see.
I hope you decide to stop drinking and move forward with your life.