Tell him that although you would love to have another baby you don't think you are ready either physically or emotionally. Tell him you want your baby to have a chance to be spoiled by both parents and be a baby a couple more years. He needs to bond with this baby. Let him know you want to work on the marriage first.
I still think you need to try this...
Life's challenges are not supposed to paralyze you, they're supposed to help you discover who you are. -- Bernice Johnson Reagon