I feel like I should not exist, I feel so empty everyday

I can't focus on things. I can't talk or answer properly and stutter so much because I can't think straight. I can't socialize at all so I don't have anyone near me. Except for my cousin. I always think like everything about me is so terrible. Probably others think so too. I just wish to disappear 

What can I do to fix this mind set or avoid thinking like this for whole day?