need some help!! please..?

one of my closets friends REALLY likes this guy in our year, since last year i think.. anyways, if it was any of my other friends i would just have a private chat with them with cookies for comfort, but.. she has been through a really tough time with home life for a long time now and i just don't want to break her even more.. she is always telling me how much she likes him etc etc.. and I've already asked the guy if he has his eye on anyone (casually) and he said that he wouldn't date ANYone in our school and he does know that my friend likes him. he told me that she isn't really his type and he likes being her friend.. so how can i tell her that its not gonna happen with them two? or should i mention it at all?? like i said she is going through a really tough time right now.. i just worry about her. many thanks to any suggestions :)