How to tell my fiance I need space

I been with him for 2 years now and engaged 1 year. we are a young 20 year old couple and have similar values in life. I love him very much and dont want know one but him. I moved away to college and that put a strain in our rlationship. We argue more these days and I feel very stressed. I failed all my classes and is going to have to go to a community college because of me stressing over him. I do admitt, I always call him and questioning him. but he have his flaws to. He palys the video game all dame day! and every time i want to talk on the phone, he cant get off to talk, he have to stay on!!! It stress me out because i dont see that in my future with him. everytime i ask him why he cant just talk to me instead of doing both, he yells and says things like " i do what the f*** i want, and because i want to!" i find that childish.also, i would always have to remind him to do things and he takes it as im trying to control him when im not. Im just that type of person tohelp ppl and plus he forgets to do things. Im not saying that i want to break up, i just need to worry more about myself. i need to find myself and have free time.i admitt my problem is that i always call him and worry about him but do anyone hav e any advice on how i can slow it down, while not given him the hint i want some space. Beacuse when he notice what im doing then he is going to get mad and think i dont want to be with him anymore... i dont know... any help?