Girlfriend of 3 years has ignored me for the past 4 days?

We had a fight and she left thr house and she won't answer my calls or texts. Every time we fight she ignores me I realized that she had been turning her ringer off at night So I asked her to unlock it for me and she said no. So I said unlock it or we are done. If u don't have anything to hide show me. She said no and she left. And she has ignored me since then. I hate being ignored. I have a lot of mixed emotions right now. I don't know what to think about the whole thing. Last time she ignored me I saw some guy dropping her off at het car. And she said its just s friend. It's nothing. I don't wanna talk about it. And I stayed with her. I still love her and care for her I need to let go don't I. The more she ignores me the more I want to talk to her.