If it were me, I would throw her out to the street. That's a hard thing but it would be too much for me. Under certain circumstances I would forgive adultery but I couldn't live with her ever again under the circumstances you describe.
God can restore your relationship. You have to really pray about this and see if that's what you want and see if it's what she wants. You have to find out the root of the problem. There are reasons she committed adultery 3 times, that you know of. I wouldn't be surprised if it's more. There is also a child to consider. Chances are it's not yours. Overcoming that and never having any thought of adultery and betrayal eat at you is more than most men could endure for long.