I'm going to look through my ex's phone and then leave her
Why do you want to look through her phone and leave her as well?
The stupid bitch shouldn't be here with me after what she did to me!
You should be more trusting of her, it's important in a relationship. You should stop being so negative about her.
Fine! I'm going to stay here and the hell with her then...
It is really important to try and trust your partner. If she cheated on you at some point then it makes since why trusting her may be difficult. If this is the case, you may simply want to end the relationship since it can be hard to fully trust someone who once cheated.