if you stand firmly on a self-lain foundation of patience and trust, someone crossing your boundaries is not so threatening. let them in. see what they do in your space. remove yourself if necessary.
What makes your mind stronger, and more able to control your emotions, is internal discipline and toughness. No one can teach you this skill; you cannot learn it by reading about it. Like any discipline, it can come only through practice, experience, even a little suffering.
i think too many people are assuming that they can turn on a "artist" switch after years of making money doing something. probably most confusing while working broadly in the creator world
don't underestimate how much the game you are playing changes who you are