She didn't yellow it is her husbands child that not any old man.
Op this exact same thing happened to one of my best friends.
She found out a month before her baby was born.
She has been through it and come
Out the other side. There is so much good advice on here and he is a cunt.
You will get through it. You will. You have absolutely got this.
There will probably be a day he tries to get back with you once the newness of his affair relationship has gone.
The other women has gotten a cheating prick who did all of this at your most vulnerable point. She will never be able to trust him fully. If he did it to you carrying his child he will do it to her.
I'm sorry this has happened to you and I hope you are ok.
What an absolute dick he is.

It will be hard emotionally but get your finances sorted. Get him out of your life as much as you can.
Revert to your maiden name, call the baby your maiden name and start divorce proceedings.
It's not what you planned but it is what you have to plan now for your and your baby.
Xxx