I am sorry that you are going through this. This may not make you feel better right now, but maybe it will help eventually.
I realized that the only way H would ever see that I and our R were not the only sources, not even the major sources of his unhappiness, was for him to leave believing that his leaving would bring happiness.
When they leave, as painful as it is, it does give you some peace. This allows you to focus on yourself and work on yourself. It actually will give you more strength. In the meantime, as you are getting better and better, she will get worse and worse and eventually, her theory will collapse.
Hang in there. I know this hurts, but you will be okay.