everybody deserves a second chance. maybe even a third, a fourth.. that depends on how much u love this person.
however, change has to come from within him. for him to be able to that, he must will it himself. giving him another chance doesn't necessarily mean you will be sitting in the corner waiting for him to man-up...
i'd say, give him all the time he needs while life goes on for you... after all, the baby should be the priority in this predicament.