Not sure how much longer I can do this

My mother passed away in 2019 and I’m not sure how much longer I can do this anymore.  One day I feel invincible the next I want to end it all. The constant self-torment/sabotage and grief will be the end of me. I’m so socially awkward I cannot seem to keep a friendship going and have no friends as a result.  I find it hard to talk to people about how I feel out of fear. I can be in a room full of people and feel so alone.  I cannot understand the reason for my existence.