Well, that's the difficult part about boundaries--enforcing them. It doesn't matter if you explain them or not, but you do have to enforce them. In fact, explaining them sometimes gives us the expectation that others will then abide by our boundaries, thus creating more frustration and resentment when they don't.
Deciding you don't want (fill in the blank) in your life is easy. Actually NOT ALLOWING (fill in the blank) in your life is the hard part. Is it worth the effort? Only you can decide.
L