April is completely right, it’s time to move on. You mention that she seems comfortable and relaxed and appears to be the woman she had wanted to be, and thats because she is now all of them things.
She has moved on from you, which she no doubt did several months ago emotionally and physically, and is leading the life she wants to lead. You need to stop over analysing her situation with her fella. It doesnt matter what they are too each other or what type of relationship she now has with him, because it’s hers and his life and she has moved on from you.
Stop beating youself up about the car he has bought her, or the expensive clothes etc she was wearing, because he has spoilt her both financially and sexually for a long time so none of the materialistic things should come as a surprise.
Letting go is hard, incredibly hard, because you clearly still love her. But that ship sailed a long time ago and like it or not, accept it or not, she is with the person she wants to be with and that person is not you.
You have to move on because she has found the life she wants and needs and now you need to.
Good luck x