How can I get my mom to have some ambition and show her that she's ruining my siblings lives?

A few months ago, my dad died. He was 51. He left behind 8 kids, myself being the second oldest, and the only one that doesn’t live at home. The kids that are still at home are 20, 18, 13, 11, 9, 7, and 5. They are all (with the exception of the 20 and 18 year olds) homeschooled. Since dad’s death, my mom has decided that she is not going to work, but expects the community to support her. My older brother moved back home after dad died, and pretty much just mooches off the generosity of anyone that tries to help my mom. My 13 year old brother believes that he is going to end up getting an education that is… shall we say… less than fulfilling. (His exact words were “I’m going to end up retarded”) My mom does not leave her room durring the day. She stays on facebook and craigslist nearly all the time. And while there is nothing wrong with either of those sites, you can’t sit surfing the web when you have seven children at home who still need your help growing up. When I stop by, the house is always a mess. The 13 and 18 year old tell me that they try to keep the house up, but mom always tells the younger siblings they don’t need to help. When she comes out of her room, she screams, cries, and runs back to her bed. I understand she’s depressed because she doesn’t have my dad anymore. I’m still sad about it, myself. But the fact of the matter is that she now has a family to support. She’s not disabled, she’s not elderly (she’s 40), I think she needs to stop waiting for the world to take care of her and figure it out. I’m 19 and I have two full time jobs. I don’t have anyone to support, but I’m starting to feel like I’m going to have to take care of my mom and siblings if my mom doesn’t get it together. How can I show her she is hurting herself and my siblings by neglecting them in the way she does? All of my siblings tell me they fall asleep crying because of her. It’s breaking my heart and I don’t know how I can help them!