Alcohol has a way of lowering your inhibitions, relaxing your strength to hold back and opening the doors for you to say what you feel. A person I know has been holding things in, taking things into account for the week and then on a binge over the weekend will spill it and say what they feel. Followed up the next morning with apologies and saying things to make up for it.
Sometimes what they have to say can sting a little. Other times it cuts deep to the core of what is really going on. Either way, it is things that needed to be said. Obviously there is some amount of pain on both sides so really, no apologies are necessary. Because they are a good friend, they can say these things. Truth hurts. Funny this, it is almost an expected ritual we have.