Read before you judge

I had to end my relationship with my live in boyfriend 5 weeks ago because he was not making me happy anymore and taking me for granted . This was obviously not what I wanted and I took about six months of denial and fighting myself to finally get the courage to tell him he needed to leave . After talking to a therapist for the past month I have realized he was a complete sociopath/narcissist and in currently on the mend . He tried to fix things for a week but when I didn't cave in and make him feel his actions were ok he decided to stop talking to me . He is now dating a girl he met on Facebook who has a child and he has already met the little girl and brought both of them to his moms house where he's living . I know he's my ex and I need to let it go but it hurts extra bad that he's dating someone with a child because I miscarried our baby last year and he couldn't even handle making me feel loved and supported but he can date someone who has a young child . His own mom says it's not going to last and she dosent know why he can't be alone and she knows he's hurting and to give it time and all this stuff but this is consuming my life I live in constant state of anxiety and I truly don't know how to handle this . Has anyone gone through something similar ? Can anyone lend me some advice ?