Thing is, the Brutii have senate missions that focus largely on taking Greece ealry on. Unless you stop them, they will keep coming for you.
Im still debating whether to attack Italy, especially as like your, I have trouble in the north with Dacia and Thrace.
Its funny though, I never seem to have so many factions working against me when I play the Greek Cities, yet they are pretty much in the same position as Macedon.