I understand what you are feeling. My father passed away in 11/97 eleven years later my Mom passed away in 2/08. In September of 2014, my oldest sister died suddenly of an aneurysm I was in the room when it happened, that is an image I still see sometimes when I close my eyes. Her husband of 43 years and high school Sweetheart had a severe stroke in November of 2015 and he passed away at 11:00 pm the night before Thanksgiving. He was like a second Dad to me.
5 days ago my other Sister passed away. I'm not completely alone I still have an older brother, though he doesn't come around a lot and I hardly ever get to talk to him. I have never felt so alone in my entire life. I too feel depressed, irritable, emotional, and disconnected from family and friends. My husband doesn't understand why I am so depressed all the time. He thinks that just because I am on Antidepressants that I shouldn't be depressed. I wish you many blessings and brighter days ahead, I will include you in my prayers, God Bless you.