How to be a better girlfriend

I’m not sure if this is the right place for this kind of post but I just need to get things off my chest. Sometimes, well all the time, I feel like my boyfriend can do so much better than me. Mostly because I’m not the hottest girl out there. He always tells me that he doesn’t want anyone else. But I also feel like he can do so much better than I because I kind of treat him like shit. The kinds of jokes that I make and the people I talk to. I just feel like in mentally abusing him and he does not deserve it. Sometimes I don’t think before I speak and the jokes I make are just bitchy. I know I can be a bitch. But I’m going through shit mentally and I feel like it’s affecting the way I treat him or the things I say to him. I don’t know how to fix things sometimes. He doesn’t deserve it and I just don’t know what to do. I need to treat him better. I feel like a terrible girlfriend. And he can do so much better. Someone that doesn’t made rude jokes. It’s all play. But I just feel like I do this kind of thing too much and I love him more than anything. He does so much for me. I do not know what I would do without him. I just want to be a better girlfriend. A girlfriend that he deserves. I need help ☹️☹️😭