Mental health

Ok I was doing so good. I was working out had no problems in the world and then bam. It feels like I have been hit by a bus. I can’t workout can’t like do anything because of how I’m thinking. I have put on weight witch stresses me out even more. But I feel like I’m not important like I’m not supposed to be on this earth. So basically I feel like I shouldn’t be alive and I feel like I hurt everyone. I don’t know how to fix how I feel or why I’m thinking like this?