Telling the father after the fact

Has anyone ever told the father of your child after you gave birth? I've been thinking of telling my baby's father...I didn't involve him during the pregnancy because he caused me so much stress (he went crazy) and got a little abusive so I left. I also found out I was pregnant when I was 16 weeks. I just don't know how I would go about telling him. She will be 2 months on the 4 of September..please no judgement I'm just trying to make the best decision as a parent which who know if I am