current problems

I've a problem here. I'm with a friend but she's not loyal to me at all. I've been with her for 2 yrs already. I have a feeling that she's making use of me. First she'll say that she wants to come to my house to print her homework, I've always given in to her. So, as time passes, she began coming my house more often mostly is to use the printer. Is my "giving in to her" harming her and myself? Well, sometimes after she has done her homework and print her homework, she'll ask me to let her play facebook, as usual, i also give in to her then after playing, she'll go to the kitchen with me to take food to eat and sometimes, even bring home the food. As time passes, i began thinking "am i being used by her? She's not loyal to me, so i think, she really is using me." Well, as soon as i began thinking about that, i began to start considering the thought of servering all ties with her as soon as possible in case she uses me more often. Since, its the end of the year, of course, the school will issue the class we're going to next year. I was looking forward to that day and I knew i was going to a different class and I did go to a different class from her. Now, she wants to come my house to print her things again but i told her say that i'm not free then she ask so many question that urge me to let her come my house. Now, I'm thinking excuses to not let her come my house so that i can server all ties with her. But what excuse can I give, she's not so easily fooled. I know its not easy to server all ties with a 2yrs friend. but I'll try to think of some ways then... I'll consult some people whom i know to give me ideas.