<human>: Can you provide a brief overview of the text?

So in short, my girlfriend and I have been together for about a year. When we first got together my girlfriend was talking to another guy who has periodically made appearances throughout our relationship. This person was a close friend from out of state who she had sexual encounters with a year or two ago but everytime they speak he finds a way to try and bring up recollections of these moments which she doesn't participate in; however, the other night he messaged asking how she was doing and she replied with "Oh look at that, you care again."
I know she sent this message because I saw it, but she deleted the conversation afterwards and when I asked if she said anything to him she denied it. I tried to make it as obvious as possible that I knew and pleaded with her to just be honest. They have had no contact since that message that I know of, but she lied to me about replying to him saying she didn't care anymore.

I honestly never thought I would be doing this, but I have nobody to go to about this and I need advice.
<bot>: Girlfriend lied to me about talking to somebody she's had sexual encounters with in the past. Don't know what to do.