Why is my relationship with my mom so aggressive?

Me and my mom argue all the time. I annoy her and she annoys me. The trouble is though she calls me a stupid cow or something along those lines for no reason. She says that it is because my behaviour is bad but I have difficulty in 'being normal'. She says I am not normal at all. This is because I have the urge to say the word 'blue' quite often and I feel that it relieves me of a bit of stress but usually she will tell me to shut up and stop being stupid but she doesn't understand that I can't help it. I have tried but I felt like my whole gut was about to explode into my mouth. Anyhow I am considering suicide over this because my mind is messed up and foggy and I keep on wondering what I have done wrong. When I get angry I really do get angry and am prone to thumping walls or slashing my wrists in an attempt to relieve it and my anger gets worse when around my mom but in the back of my mind I know that she is the closest person I have got and she is the best friend I will ever have. I just can't comprehend our relationship though. She doesn't understand me at all. She will usually become a bit nicer to me when we have got visitors and they always say how much my mom cares about me and stuff but when they have gone she returns to her grumpy old self again. What shall I do to improve it a bit?