boyfriend left me

My boyfriend cheated on me and has left me for another women. I have to keep living with him for another 3 months
Although I am going out and doing other things, I find myself constantly thinking “he replaced me” and “he didn’t value our relationship” and trying to find reasons about why he could have done this to me. He doesn’t show any type of compassion or sadness

I struggle to think of other possibilities, because he DID replace me and I feel extremely betrayed