I think my boyfriend has been complaining about me to another girl, am I right to be upset?

Anonymous
It's sort of a long story but I'll try to short it down. I was using his phone (because he was cooking and I needed to reply for him), and I had to insert something I had copied to the message. So naturally I open the clipboard, where I see a screenshot of my texts with him where, to be fair, I was being quite unreasonable. It's worth mentioning that I have really bad anxiety, and he is aware, so sometimes I get overly concerned and unreasonable, and it's also worth mentioning that this little spat was resolved within minutes of the screenshotted thread. He has a girl friend from university who he texts quite a lot about random stuff, which I have no problem with, but I know for a fact that she is the knly one he would have sent it to, I don't like the thought of him going to another girl complaining about stuff that just isn't her business. I also haven't met her, and I don't like making bad impressions on his friends before I even meet them. I don't think I'll be bringing it up to him, since I think that might make him think I don't trust him and I never want to make him feel like that.
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I think my boyfriend has been complaining about me to another girl, am I right to be upset?
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