It is human nature to want to know what is going on. Your h may have called the cruise lines, out of curiosity, to see what it cost or where you might have gone. It may be nothing more than him being curious about the trip. If he is planning one, he probably needed info about the destinations, number of days, and costs. For all we know, he could have been on hold for a while before someone actually spoke to him.
Retaining a PI is expensive, but you could very well get some answers to your questions...but the bottom line would be....would you feel better knowing exactly what he is doing or would you be better off moving forward and leaving things along?
For me, retaining a PI answered all of my questions and I was able to move forward and I did not inform my xh about his stupidity in inviting the PI in for a sandwich and a beer and just talking to him about the previous tenant. I will say this, my xh was a very neat, orderly person pre crisis, but became a piggy in a sty once the crisis kicked in. The conversation that he had w/the PI checked all the boxes that he was definitely out to lunch.
No matter what you do, you can't change the course that he is on. You can only control the course that you are on and you will need to find a way to ease your anxiety. One way is to make sure your accounts are watched closely. Do a credit report to ensure that there are no "new" loans or credit cards that you weren't aware of.
Continue to come here to vent. Grace, I think you are doing well. You are just having a few moments of anxiety whenever he does something. Take a deep breath and know that you are right where you need to be at this time.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.