controlling relationship

so I've been in a pretty serious relationship for the past four months. there's been signs a long the way but my boyfriend has become very controlling. I would understand if I was doing things for him to get angry at me but it's gotten to the point where I no longer talk to my friends, do anything outside of work, and he even takes my phone to work all day while I'm stuck with a phone that only works with wifi and he proceeds to get mad at me because I'm not constantly texting him because my wifi at work is a hit or miss. It's little things like this that he gets mad about. I love him very much but I'm not sure so what to do anymore because no matter what I seem to do he has something negative to say or something to get mad about.. it's becoming exhausting.