Did Bruce Betray Wallace?

Robert The Bruce Never Betrayed William Wallace

Robert the Bruce did bide his time while Wallace was in hiding, until he proclaimed himself King of Scotland in 1306, the year after Wallace was captured by the English and executed.

Did Robert the Bruce know William Wallace?

Although they were alive at the same time, and William Wallace was Guardian of Scotland immediately before Robert the Bruce, there is no evidence that the two ever met.

Did the nobles actually betray William Wallace?

According to the movie, the Noblemen Mornay and Lochlan broke their promise to Wallace after being bribed by Longshanks. The ultimate betrayal occurred when Wallace discovered that Robert the Bruce was fighting alongside Longshanks after defeating him and pulling of his helmet to reveal his identity.