Two weeks ago i found out that my husband of 4 years slept with a friend of his. I was out of town at the time. He said that it only happened once. We decided to try to recociled our marriage that was until she called to say that she is pregnant and wants this child. In the book surviving an affair states that one should totally separate themselves from the person that they had an affair with. How is that possible in this situation? And how can our marriaged be recociled?

It is posssible to do so during the course of the pregnancy and waiting to have DNA done. That is the procedure used by my H and I.
Hence, that time gives your marriage the time in which you can begin the process of healing, rebuilding and reconciling your marriage.

There are many on these boards (and off) whose marriages have survived, and a few whose marriages did not. You'll never know unless you try; if you don't try, you'll always wonder, and you should address the issues (counseling, reading, discussion) that caused this to happen in your marriage, or it could happen again in the next relationship.

Some decide no-contact with the child, others arrange for visitation with minimal-to-no contact between the bio-parents; there is no reason they should have solo contact ever again (!), even when there is visitation. You and your DH can become a united front, a team, again.

Read the MarriageBuilders policies for a good marriage and to affair-proof your marriage. Is he remorseful?

Hang in there and keep posting. I'm very sorry for your pain.
J
married 19y, 3 kids together
DH's affair 8+y ago
visitation w/OC