Husband Sharing Hotel w/ Woman

My husband is traveling for an interview and will be driving about 6 hours away. We have an 18month old and a 5week old so I will not be accompaning him. He asked a friend to tag along for company and has had this trip planned for weeks. He will be staying the night in a hotel and returning the next day. Well tonight, 2 days before his trip he informed me that another friend will be joining them, a woman. She is a former classmate of his and I have never formally met her. He tells me that she will be staying in the hotel with them. Now, these friends are only going to keep him company because I can't go. Am I wrong to be upset that A. He tells me that a woman is going with him 2 days before the trip B. He never asked me how I felt about it and C. Both the other man & her are staying in the hotel room with him. The other man going with has a girlfriend, and my husband says this woman has a boyfriend. He said I am being rediculous to be upset and that he doesn't think it is a problem not to ask me about how I felt. I am really hurt and upset. How would you feel?? How would you handle this situation??