Okay first, break up with the poor lad rather than throwing "hints".
Get him one to one, and tell him it's over! Make sure it's drilled into his head.
I think he'll be really upset if you just dump him then run off to his mate, I mean give it time at least!
Just don't expect him not to be upset or angry when you do date his friend... Because it's more than likely he will be. .
Just be careful what you do.