
He is disappointing me even more because he was the one who seemed caring and as if he truly loved her, but now it appears that he is doing it for the ex-husband to find out at least that the ex is honest about being a jerk and not hiding behind good acts like this younger guy acting like a kid and not caring for her feelings, given how much she has already suffered.

Even if he understands what she went through and why he continues to hurt her, it appears that he is not making any progress and is really worsening her mental health. Be with her completely if you like her. It is heartbreaking to see her suffer any more than this. Seeing her, I feel she is better off single than having any partner in her life. All she has ever been is disappointed by relations.
She already battles with her thoughts, which are hurting her mind until nothing good can reach it, but he only seems to push and pull away. His interest doesn't match his words; still, he tries to act differently, like it's love I am still not sure if he only likes the idea of having power over his ex-husband or if he ever really liked her to begin with.