Infidelity Support Group
Any relationship in which one partner engages willfully in sexual relations with another outside of the partnership is considered to have experienced infidelity. This breach of trust is often traumatizing for the faithful partner as well as the relationship, and support is often needed to heal emotionally and to decide whether or not the relationship should continue after...
My prayers are with you!
If you are not sure, you will have to wait. Who knows how you will feel if the healing is not complete and you have a baby? Will you be able to be the husband and parent you want to be? Will you feel that you were coerced?
I think you need to let her know about your reservations in having another child so soon. Let her know that you understand what she wants and you would love to have another baby with her, but that there are issues of trust and honesty that need to be dealt with first. Also I don't think she understands how deeply hurt and angry you must be with her for not only having the affair in the first place, but also carrying on the contact with the OM.
Whatever you do, don't feel pressured into doing anything you are not comfortable doing. A child is a massive responsibility in a stable relationship let alone one that is teetering on the edge.
You're a smart guy to actually have the prescence of mind to think about this decision you are about to make.