Depressed And concerned

I don't know what to do with myself anymore. In the morning, when my sister is around, I'm fine. I can play video games, and talk about doing things. But at night, listening to my sister party online with her friend, or even while I'm doing chores, I feel like I'm too depressed. Too depressed to post things online, too depressed to talk to people. I know people won't be happy when they know how I'm doing, so I don't want to talk about it. Should I be on the internet, be putting potentially upsetting content out there, make a big fool of myself, if I I know it'll all result in nothing?