Complex sentence: Gwendolyn is distressed about her possibly being a murderer and breaks down, also remarking to Gideon that he has been behaving himself very rudely toward her the whole time they have known each other, but begins to cry during this, so Gideon comforts her.
Split into simpler sentences: Gwendolyn is distressed about her possibly being a murderer and breaks down, also remarking to Gideon that he has been behaving very rudely toward her the whole time that they have known each other. Gwendolyn begins to cry during this, so Gideon comforts her.