How do married people do it!

I've been in a relationship with this guy for a while but just recently I found out he has a newborn child and he's been telling his child mother the samethings he tells me...that he loves nd wnts to get right with god nd he wnts the best but he said he dosent love her nd that he only said it to see his son they had sex one time nd she was pregnant he says his childs mother doesn't wnt anything to do with the child nd he plans on getting full custody of his child nxt month...he is a great guy nd me nd him have the best of times together he wud give his last for me nd he has but im beyond hurt nd so confused on what to do pls give advice.