Can’t handle the pain (ranting)

My fiancé and father of my three year old son had an affair with his ex during a time when we were basically at each other’s throats. Mind you this ex of his had been stalking me, got fired for looking through my medical records at work, ruined his car and tried to sabotage his job. She decided to message me about the affair because she’s pregnant and my fiancé told her to get it aborted. (So basically she wanted to hurt him since he hurt her). After some long thought and consideration and some tequila I decided to work things out with my fiancé. But I’m so angry with him for bringing the chaos in my life. She’s probably around 5 months pregnant and even if I left my fiancé I’d still have to deal with her since our kids are gonna be siblings. It’s just been 2 months since I found out and although he’s been sweet and caring and trying his hardest to mend fences, sometimes I get so angry I want to punch him in the face. I hate his ex for how she harassed me and I hate him for bringing her into my and my son’s lives. I’m not sure if I’m gonna be able to handle this. I love him but all I feel is pure rage.