A.,
You've been given a lot of good advice, and I hope some of it rings true for you and you can find some ideas to try. Here are a couple more thoughts.
What you are going through IS a relationship killer, especially when (1) the marriage isn't consumated, making it easier to get out of and possibly making the attitudes of those in it something less than fully committed, and (2) because you've both obviously used the "exit strategy" to "fix" a relationship problem before, and that makes an exit more of a possibility again. Consequently, this needs to be handled with great care if you're going to preserve the relationship.
I am with the writer who said, (gently) remind him that he gets to come home at the end of his work day, and that you do not seem to have an end to your work day. Since he is a chaplain, appeal to that part of him - ask him to put himself into that frame of mind and consider how he would deal with a family who approached him with this problem - husband working very hard, wife exhausted from dealing with a small baby and four other children's needs, and a shaky seamed-together family made up of kids from other relationships.
Also, I strongly suggest that you take yourself to counseling! I don't know Tulsa, but most communities have sliding scale counseling services through the county health department, if money is an issue. Tell him that you want counseling to help you with the stress of the situation, and invite him to attend with you - either just the first session or occasionally as issues need to be dealt with - or whatever the counselor suggests.
At any rate, feeling like you are being taken for granted, and that your concerns about the baby, your work load, etc, are falling on deaf ears, will make you resentful, angry and I predict that he will ultimately blame you (your anger responses) for the problems in your relationship - even if it's his refusal to pay attention to your needs that got you so angry in the first place. He needs help in taking his share of responsibility both for your well-being and for the child-care, either by appealing to his inner chaplain to recognize the truth of the situation or through the help of a third party counselor.
Good luck. My heart goes out to you.
S.