Overcoming Insecurity

This is one thing that I do not know how to do. 

Big picture: I am an independent, educated woman who happen to be married. After a painful divorce in 2014, I remarried in 2019 to someone I love (well I loved the first guy too but it didn't quite work out). 

Hubby was single when he married me and had a lot of female friends. Not a problem, because I embraced all that he is/ was. He also has a lot of male friends; it is his personality- he makes friends easily [CHECK]. He has his own schedules [CHECK]. He has activities related to work that requires him to travel [CHECK]. He has many nieces and nephews who are really attached to him, and typically spent their holidays in his house to this day [CHECK]. I even slept at my own house those nights, to allow the space & not be the 'difficult aunt' [CHECK and CHECK].

Why do I have this niggling doubt, that something does not quite add up with this person from his past? Why can't I let this one go? This person "A" used to stay in this house when she was studying. He considered her as his own niece, because he knew her dad. When she left, there is a locked room full of her things untouched for years. We are coming into our third year of marriage and her things are still in the room. TAKING ADVANTAGE MUCH????

He allowed her to use his car to pick up her things last Saturday, and I thought she will take every damn thing. She took 4 boxes that could have fitted into a small boot. 95% of her stuff remained in the room, irritating me. I have half the mind to call a mover and send all of it to her preferred address, or I can just dump them off at a junkyard. These things have not been needed for THREE years minimum; what are the chances that they'll be relevant now? 😔🤔 

Another niggling question: who is that person she brought with her? She claimed that this person was  a friend during her masters study, or is she? One of them had said I looked thinner compared to the last time (he said) BUT THIS IS THE FIRST TIME WE HAVE MET, OR AM I MISSING SOMETHING??? Just Who The Hell Are These People!!!???

Unfortunately I am already in interrogation mode. I am praying that I survive the night. S.O.S.