Boyfriend impregnated his ex

So I found out that my boyfriend of 3yr got his ex girlfriend pregnant

I had the urge to go on his phone one day after I came from work and that was the day he went to see her in the hospital

And in message it said something about your going to be a dad I couldn't read anymore I felt sick (obviously he knew about it she was 7month into it)

We end up having big argument

He said it was a donation and she was trying to have a baby with her boyfriend at the time and it fail because she is getting to that age

And he doesn't want to have anything to do with it and that he was going to tell me about

His mum and dad know about it

The next day after that argument she come over because he was supposed to come visit her again but he didn't

Since that day she would call his phone eveyday multiple times even at midnight until the baby was born

He didn't sign the birth cert so she came over and he didn't want to open door (I know this cause she called his dad and told him that she is at the house and want him to sign the birth cert)

He said that he would go to see the baby with his dad I agreed

Few months later he says I need to go and see the baby I asked if his going with his dad

He said dad not feeling well because of the weather

I said to him I agreed with you going to see the baby with your dad

Then ended up in another argument and im over it I love him

I said just go do whatever you want to do

They have only been text and she is always sending him pictures of the baby

Help Andy advice