My girlfriend's brother is upset with us because we didn’t let him stay at our house.

My girlfriend and I recently moved into a private house about six months ago. We're still in the process of furnishing it and currently only have one bed for sleeping. During the holiday season, my girlfriend's brother returned from abroad. A few days after his arrival, he informed my girlfriend that he would be staying with us. This was a definitive statement rather than a question, and he didn’t clarify how long he intended to stay or check if we even had space for him. He simply assumed that since we live in a house, there would be room for him. Generally, we had a good relationship with him, and we had jokingly mentioned that one of the rooms could be his. However, this was all in good fun, especially considering that during the construction of our house, many, including my girlfriend’s family, questioned why we needed so much space for our 80-square-meter home. When we first met after his announcement, it was at dinner at our parents' place. At that dinner, he asked my girlfriend, “Have you prepared a bed for me?” My girlfriend attempted to explain that he hadn't even asked if we were okay with him staying and that we wanted to spend quality time together during the holidays. She also mentioned that he had other options, such as staying with their parents. He reacted strongly, expressing his upset and even tried to shame us in front of the family by saying we were denying him a place to stay. Interestingly, he still hadn’t booked his return flight back to the country where he works, more than a week after this incident, which suggested he might have expected to stay with us for up to two weeks. Since then, he hasn’t communicated with us. He’s in his mid-20s, older than my girlfriend, and I've noticed similar situations where he prioritizes his feelings. This situation is taking a toll on my girlfriend, as she feels sad about the fallout. Ultimately, the decision not to accommodate her brother was mutual between us. Yesterday, my girlfriend reached out to him via message, attempting to clarify that he might have had unrealistic expectations and that it was partially our fault. However, she also pointed out that he should have communicated better and initiated a discussion instead of making demands. He responded with an aggressive message, criticizing us for not allowing him to stay in our "big house" and dismissing our concerns about lack of additional bedding. He claimed not to be angry, just disappointed, and mentioned that he just wanted to spend time with us. He also made a comment comparing us to their mother’s sister and her husband, who do not communicate. What should we do in this situation? How can we resolve this amicably?