I am so sorry!
If he's willing to walk out on the mother of his child to pursue a 1-month-old "relationship," then YOU'RE BETTER OFF without him. Seriously. Despite how he represented himself or how you may have seen him before, we're probably not talking life partner material here... either that, or maybe there wasn't an agreement on the depth on your relationship.
It'll take time to get over the pain and the betrayal and learn to trust again... and postpartum hormones are not gonna be helpful, so watch out for postpartum depression signals even more carefully now since you've got emotional trauma piled on top of that. Contact your doctor for that if you need.
All that said, his relationship with you and his relationship with his child are different. He does have rights to be considered, if he even wants to exercise them. Also, he's obligated to provide for the child, so do everything within your rights to hold him liable for support if he isn't forthcoming with financial support.
I hope you have a good support system to help you. :-) Wish I could do more than give you a smiley.
