I need some brutally honest advice.

Alright, so. I'm super clingy and needy, with my boyfriend. I need his constant attention all the time. When we are hanging out, when we are not, when he's at worl, ect. Like I'm always waiting for him to text me and play games with me and stuff. And I get mad when he doesn't or want alone time. I need advice on how not to be so clingy. Like how can I enjoy being alone without needing him and his attention. I know it's causing problems between us. And it's messing with my mind. I'm barely happy anymore. Mostly cause of that. Can I have some advice? Thanks in advance.