I overthink a lot and stress about issue

I overthink a lot! Due to which I am not able to behave good with my partner. We fight a lot. My studies are getting affected by this and I have lots of anxiety issues. I can't concentrate and which makes me a mobile phone addict. My main issues is that even if I do something or the other I just say bad things to my boyfriend and which in turn makes it a very stressful relationship for both of us. My friends circle are not that good either! Each and every friend of mine is against me and no one in my class talks to me. This bothers me a lot and I think about this issue way too much than I should not. I can't control my mind of thinking negative. Sometimes I feel like suicide. I don't concentrate on anything. I don't have any Hobby or any passion. Everyday I feel like having something sweet and there is this sweet rush in me. I am not able to open up with my boyfriend.