Th mf cheated

Don't know where to start, but my fiance cheated on with his ex while I was on a vacation and I was 3 monts pregnant. I'm numb and don't how to feel. Specially because he is so a socially awkward person and actually talked so much shit about cheaters and one of our coworkers committed suicide after he cheated on his wife for so many years. Anyways I never expected it from him and in my past relationship I was cheated so much that I knew what were the red flags but with my fiance was different I never saw it coming and now I'm sitting on my couch numb. The mf had the audicity of wanting to leave when we have a 6 weeks month old, a 1 year old, and two other kids from a different marriage. The only crazy reaction he got from me is that he didn't get to leave and I decide what he gets to do at this point. Crazy but at least I deserve that the choice of kicking him to the curve or think through it. I will more likely kick him to the curve but like I told him I choose to that not him leaving with all the damn responsibilities, I deserve the time to figure out how I may going to take carw the babies and the other kids. I say this because he loves to run from responsibilities and go to his parents because those people don't clean his butt because they can't but they would if they could.