My girlfriend always gets upset and does things out of spite. How do I handle situations like these?

My girlfriend and i got in an argument because i didn't give her my debit card number for I don't feel comfortable giving that to just anyone since it is my privacy. She says because I don't trust her and she threaten to leave me. She usually does this when she gets upset and doesn't get what she wants.

When my girlfriend gets mad at me she tends to act passive aggressive with me. She talks less and when I ask her what's wrong she just says" nothing is wrong." Today she mentioned her ex and told me how her ex of 7 months gave her his debit card and telling me how he is better than me. She even told me she texted and started talking on the phone with a guy I don't feel comfortable of her talking to and she promised to stop talking to me and does it now when she is upset. And she even told me she loves her ex more thane because they both trusted each other. She even curses at me saying "go fuck yourself" or " fuck you". Those words don't hurt anymore since she usually says things like that when she is mad. I just act calm. I know she only does it out of spite and to break my equanimity. The more clam I am the more she seeks to does it. I even tell her to not talk to me like that or she can talk to me later but she still does it anyway until she realizes I'm not budging then she stops.

I'm just wondering why she acts like this? What should I tell her? How should I handle this situation? I don't want to leave her since I do love her I just don't like how she acts like this when we argue. I have never cursed at her or ever raised my voice because I do respect her. I just don't like it when she acts like this, it makes prolongs the problem instead of fixing. Even when I talk to her to make her feel better she even told me to not call her "baby" or "I love you" or that I trust her. Advice on what to do would be appreciated
Updates
+1 y
by the way we've been together for a year and 3 months
My girlfriend always gets upset and does things out of spite. How do I handle situations like these?
Post Opinion