(NSFW) My boyfriend would lie about other women, now I fantasize about it?

I suffered tremendously because the guy I was seeing would constantly lie about texting, meeting up with and two times sleeping with other women, and then he would verbally abuse me when caught.
Its been a few months now and I found myself fantasizing about him sleeping with other, trashy girls. It turns me on and I don’t know what to make of it.

Something that caused such trauma and pain can turn into a fantasy…? I never knew! Before I wouldn’t even masturbate because it would depress me too much to think of the pain he caused me.

Any philosophical ideas as to why?
Is it because Im finding some comfort in accepting the fact of who he is and what he did to me? By seeing the ‘truth’ or reality of him and his thoughts I find some pleasure? Uh.