Hello Abbey, I can remember the pain and anxiety I felt when I went through this with my husband. I remember the advice I received and how hard it was to follow. Looking back on it now, I am just frustrated that I did not do it sooner.
In your post, you talk about what your husband thinks about you. I would say he thinks one of two things..either you know about the OW and must not care or you would have said something by now, or, he has got you fooled because he has been cheating on you for 3 years and you have not caught him. Stop letting him disrespect you.
You need to go on your trip and hire the PI. Take the proof, because you now it will be there, and confront him. Tell him he has X number of days to get his things out of your house and that your lawyer will be contacting him soon.
Before then, if he says something about you not being happy, tell him that women that have cheating husbands usually are not happy. Do not respond to his replies. Decide what you are going to say and say it. When he tries the why, what about this, but you etc...reply that some of that might be true but you married and married people are not supposed to have girlfriends. Keep saying that until he realizes he cannot manipulate you. Stay strong.
Why would he change his behavior when he is getting everything he wants? You take care of the business and his home while she takes care of his fun and sex. He has it made. Until you upset his apple cart, he is not going to change.
I am divorced now and my husband still runs from one woman to the other. Do I wish that we were together still? Yes. But I learned that my self respect and the example I set to my children are the most important things.
M:38 H:42 T:20 M:19 D:18 S:17 MLC: Sometime in 2007 OW Bomb 1: 12/28/07 OW Online relationship 2: Spring 2009 Told him I wanted D: May 10, 2009 D final: 07/09/11