Complex sentence: Gwen runs off but returns, explaining that she is just really mad at everything at the moment and that she wouldn't have really shot him, a fact Peter already knew because his spider sense didn't go off despite Gwen's wrath.
Split into simpler sentences: Gwen runs off but returns, explaining she is just really mad at everything at the moment. She wouldn't have really shot him, a fact Peter already knew because his spider sense didn't go off despite Gwen's wrath.