Should I be her friend or not?

well here’s the thing: you said she seems like your best friend. if you don’t know for sure if she’s your best friend or not, then she’s not. you may tell her everything, but think and try to remember as to whether or not she tells you a fair amount of things going on in her life. do you hang out outside of your house? how does she act then? does she talk to you alot? just think about these things and try to get a grasp of where your relationship is at with her. a good thing to try would be next time when she comes over to tell her she can’t use the computer because you don’t want her to or its broken or something like that. and based on how she reacts you can get a general idea of what she’s there for.

now, you don’t have to stop being friends with her if it turns out she’s more intent to use your computer than to hang out with you. you can get rid of her all together, or keep her around to talk to occasionally. its really up to you and how you feel about her.