I agree with Ceejay123 but....
I have been in your shoes.Well I am in your shoes....Had my first baby 9 months ago.I don't want to keep re-living and typing the details but something about being abandoned for a teen esort/prostitute,him giving her more effort,even introduced her to his immediate family...who some of those people were labeled psycho to me but were good enough forher to meet after a month and I was there for multiple years,he is abusive to other women but not physically abusive to me...so he preferred weaker females,her having a kid 2 months ago..and im not getting a dna and signing the birth certificate...even though the kid looks nothing like him and is a huge chance not his...
Our stories are different,but similar.My advice...you will lose your mind wondering why or how to deal with that situation and your child.Coping and dealing with the reality of things...yada yada ya
Guess what the best thing to do is?
Until you are strong enough to handle things and can rebuild your thoughts,don't be bothered with his situations.Let it be strictly about your baby.Nothing or no one else matters at this point.Your heart is broken and you must take baby steps to heal and rebuild who you are as a strong woman.It is tough and I still have weak days and strong days.
I would not be bothered with any of them and focus on being a strong mother.Happy baby equals happy mom.Your child is a baby right now and molding him is all you need to care about.Let his father handle whatever else he is doing on his own.The way you two ended was harsh ,so you get a pass to not be bothered and to fix your broken pieces.If he left you that way,he will leave the next the same way.
Seems harsh,but it really helps to focus and give your all to your child.Building a relationship with the unborn baby right now is overwhelming and not mandatory right now.You gotta work on you,because the road ahead is tough and baby needs a tough mama.That should be the last thing on your mind,healing is the next step

Hugs,it hurts like hell but with strength you will make it