I recently broke up with my boyfriend, and now he has a new girlfriend. I dreamed that some that I couldn't see told them that they are causing trouble, and my ex-boyfriend told this invisible person to mind their business... it was a really wierd dream.

It sounds like the invisible preson could be a part of you that is unhappy that they got together and is angry at them. Your ex-boyfriend telling you to mind your own business could mean that in waking life you think that he doesn't want you involved in his romantic life anymore. He could also represent another part of you that thinks it's time to move on and not be involved with him anymore.