Boyfriend going out?

So yesterday me and my boyfriend spent the entire day together. At around 9pm he gets a message from his co workers asking him to go to the bar and he immediately says yes. And tells me he is taking me home. I cried and told him I don't want him to go and he still did. But his argument is that we spent the whole day together and he just wanted a drink with his friends. I'm really upset with him and not speaking to him. Am I overreacting? Was he wrong to go out?