Confusion in my relationship

Me and my girl have been dating a couple months now and we believe that she is pregnant. The situation at hand is that last month I went through her phone and read texting msg's sent to her ex about him being all that she needs. She says that she was just testing him. She had left the guy for me because I'm nice and I treat her better then anyone has ever. Now I question a lot of things such as if she still sends him text msg's like that. He still has her truck and a key to the apartment. He doesn't know anything about me or that I even exist. She said he hasn't told him because it would create more drama. I notice the small things in life. Things are starting to change and they weren't the same as the begining. She tells me that she loves me and that I'm all she wants to be with. I'm not sure what to think or even what to do. I'm so confused, she has me in the palm of her hand. I love her so much it hurts. I just need a little advice