I'm confused!! Need advice!

I was in a relationship with my fiancé for 2 yrs. I moved into her house a year into the relationship. She has a daughter that's 11 and a son that's 18. The son recently moved back home. Both kids come from different dads. I have had a great relationship with both of them. We had our disagreement like any relationship out there, but not to the point of separation. My ex fiancé was married to the little girls dad for 7yrs, but ended due to some wrong doing that he cause to her son. Since I have meet her and been with her the guy never came around until recently. From what I understand, his a pretty well off, but has poor health for such a young guy. About two months ago, he called her that he wanted to see the little girl. According to my ex, she
was scared and wanted to play nice, because according to her his a very
Powerful man with lot of legal connections. So instead of meeting in a neurtral place, she drove 6hrs to the front of his door. I knew that would be a bad idea, because his prob. thinking something more. When She came back, she became a different person. Very cold towards me. 2wks past by and told me to move my stuff out and that she needed her space. I never told her I had a feeling something happen up there, but up to this day makes me thing what did happen. Was it about money?sex? The guy having his 3rd stroke by the age 38, not too sure it could be sex. I moved out my stuff. Her family, brothers and sister were all sad and upset to find out that we weren't together anymore. I tried talking to her, but she wouldn't hear it. About a month ago, she showed up at my work, to see how I was doing and we ended up having sex later that night. Up to today I keep in touch with her family, especially her son that calls me to invite me to play ball. Her son told me yesterday that he had to spend the night at his grandma's house, because his sisters dad came down and is staying at the house for the weekend. He was very annoyed and didn't feel comfortable being there. Suddenly there spending lots of time together. I haven't talked or seen her in about a month. What's her thinking behind this? Her family is all upset in her recent decision. This is the guy that she would talk to me about with lots of angry because she lost her son for a good portion of his teenage years, because of what he did. I'm blown away. Is it a money thing or like a rebound relationship? Am I completely out?