<human>: Can you condense the text into a few key points?

Happened this afternoon, *sigh*. I don't get to see my girlfriend often so when she visits my apartment she likes to put on a shirt of mine just to "feel cozy", cool, whatever, right? She puts on an old work shirt I had from working a college night for my university. Unfortunately, due a mess up on my supervisors end, all the shirts were medium sized (I wear an extra small..) so naturally, this shirt (more like a dress) was pretty big on me. I've never worn it since, not even around the apartment. Anyways, she loves how the shirt smells like my cologne and is surprised by how well it fits on her and says that my shirts are usually a little snug on her. I, without thinking, immediately quip  about how the shirt she's wearing is in fact a medium so that's why it fits her so well. She started crying because now she thinks *I* think she's fat. fml.
<bot>: Girlfriend wore a medium shirt i had laying around, liked its fit- I told her it fits her well because its not a small. She thinks I called her fat.