<human>: I went on a two week holiday with my best friend (booked way back since before me and my boyfriend got together) and unfortunately this fell slap bang in the middle of his birthday. Nontheless, I felt really guilty about not being there for it, but left him some nice presents and things for him while I left. 

It's been about a month since I came back and we've gone back to spending the majority of our time together whenever we can. However, a couple of nights ago his friend told me he was messaging a girl on his birthday. He used to work with her, but I don't know their history, so I confronted him and asked him about it straight away. 

It took a while for him to tell me, but he then admitted that she sent him a text saying happy birthday and he replied when he was drunk and they got to talking. She was ranting about her current boyfriend and he said that 'If Amy and I weren't together, I would treat you so much better than he does'. 

Am I right to feel betrayed by this? I know it's a 'what if', so I'm not sure if I'm overracting or being oversensitive or not. 

He says he feels terrible about it and has apologised profusely since and has admitted it was a really stupid thing to do.

I know it's not cheating, but it's left me feeling insecure. I know he hates cheating, and I never expected him to talk to another girl in that sort of way.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: My boyfriend told another girl that if he wasn't with me, he'd treat her so much better than her current boyfriend does. Don't know if I'm overreacting.