What do you think, i found this on my brothers facebook?

well the first thing to do is never tell him that you were on his facebook and saw this message. that would be very bad! He is obviously going through a rough time right now with his girlfriend. What i would do is just go up to him and tell him that you noticed that he is feeling a little bit down, and that you guys should talk about it. I don't know how close you are, but if he hesitates, just force him to express himself (even if he says that nothing is wrong). He needs someone to talk to about his problems instead of letting them fester inside of him, and he did this with the GFs brother over the internet, but he should really do it with you, person to person. Listen to him, give him advice but at the same time be cautious. If you give him advice that ends up leading to the end of their relationship (even if its not your fault) he could very well blame you and screw up the relationship between you guys. That's the best I can do with what I have, and I hope that this works out for your brother!