Personality is my problem

I’m prettyish you know everyone always tells me i am and, my body is nice i was born with hips and I workout to keep my stomach and curves popping. But i am ugly on the inside and ive been trying not to. Its like when I’m being super nice I don’t feel like myself then when im being myself the things i say makes me unlikeable. Idk how to get over it. It makes me insecure to talk much because im the stuff that comes out my mouth is offensive. Idk what to do it’s the main reason I don’t have many friends and my relationships always ends so bad that they wouldn’t even speak to me again.