Do I have a right to be upset?

I live with my bestfriend and he means a lot to me. It's definitely a platonic relationship. But I feel that I'm giving more than I am getting back. When we need groceries, it's usually me who goes to the store to get them. He never pays me back and he never feels the need to actually come with me. He's low on money so I'm one to let that slide. At school, I usually end up buying him lunch and even though it's usually only a few bucks, it really adds up. Even out of school, like on weekends, he ask me to go get lunch for us. Again he never comes with me because he says he needs to do his homework or study. And again, I usually let that slide. Generally, all I ask of him is to be allowed to do homework with him, but he says no and will invite our mutual friends over and then lock the door. Right after I did a favor for him. I try to say no, and our other rooommate says I need to but when I try he just guilts me and I feel worse than if I just do it. He gets upset with me and says I never leave him alone (like wanting to study together) and I can't expect him to "hold my hand" after I do something nice. Lately I'm sad all the time and get upset really easily. He gets mad because he says I'm always crying and it stresses him out. I just don't know what to do!