Im gonna go out on a limb here and take a different approach to your situation than others have. I hope you are still in the hope mindset and are continuing to check this thread.
One of the things that i have come to believe about depression (through mine) is that it is anger turned inward. So ask yourself, what are you angry at yourself or others for? Are you angry that your sister's financial mess and the feeling that you must fix it? Are you angry that you are back at the house where there is so much pain? Are you angry at yourself for feeling you have to take care of your grandfather? Its not as easy as people say to just start thinking positive and everything will change for the better.
From a law of attraction standpoint, it seems to be a common occurance that we are brought back to a place where we feel there is unfinished business or pain because we feel we havent conquered it yet. One of the most powerful practices is that of forgiveness. You have to forgive that fact that your sister is in the situation she is, you have to forgive that you were abused, and you have to forgive yourself for being afraid of that house in the past and today. You will not notice any significant difference until you start practicing this. Loving forgiveness is the most important step.
The next step is try to think positively, as others said, this will help dramatically as well. your statement here shows that you are trying and seeing the bright side of things: "
I have the upstairs apartment where my grandparents and I used to live. My task is to clean it out, sell whatever is salable on Ebay (a great jumpstart to my store), and start renovations. I'm also helping my grandfather learn how to use the computer and go on the Internet. He's very happy, my sister is probably deeply relieved" Try and focus on creating mental statements like this. You will find that by getting closer to your sister and your grandfather, your sense of peace will change greatly. However, make sure you still have time for yourself. Your meditation will change back as well, after some time. Cant say that I know what its like getting my eyebrows done (cause im a guy) but little things like this can make a big difference as well (so ive heard).
You said he is afraid of his neighborhood, and has made you feel that way. Show him that you are not afraid, he will change and so will you. Put up a negativity wall (as i say) and do not allow things to enter. Remember that your inner thoughts reflect your outside reality. Use your heart as your guide and know that you are being selfless in taking on these tasks. Know that you are helping people tremendously.
After visiting your blog it seems like your passion is writing and expression and i think it would be a big mistake to give it up. It probably wouldnt hurt to write more about your current experience, it will help to release some of those feelings and relate to others through personal experience (they love that). Alot of great books were written during great personal struggle and discovery. I wouldnt give up on your writing fiction either, if you write short storys or ebooks, you can post them right on your blog and either sell them or offer them for free to gain traffic (seems you've started to do this).
The title of your blog is "Love, sex, relationships, and self development for the fearless thinker". Will you allow yourself to be fearless or controlled by fear? Use this time to create new relationships with your grandfather and your sister, use it to release things that have been troubling you, use it to get over your fear of that house, use it to jumpstart your ebay store (as you said), use it to increase your writing capabilities, use it to grow. You never know what may come of this but this hard time for you might yield more than one great result. Just try not to tackle everything in one day because then you will be overwhelmed, pace yourself.
I wish you the best.