It's hard to know if you're overreacting without more background.  Does your husband know how important it is to you that he attend appointments/involve himself in the pregnancy?  Have you specifically told him that?  Have you reminded him that this is YOUR first baby and his first baby with YOU?   Had the two of you, as the adults in the house, agreed that the baby would have the bedroom you planned on?  Have you told him that his daughter cannot have that room as it is needed for the baby?  

If he knows your feelings and he simply doesn't care and is favoring his older children, then no, you're not overreacting.  If, on the other hand, you have not made this clear to him, then you need to as soon as possible.  Frankly, there is no way I'd want to be living in a house with FIVE stepkids, especially with all of them being teenagers or close to it.  I can't imagine living with 5 kids, let alone 5 teens that were not mine.  A husband would have to be extremely supportive for one to live through that successfully.  From what you've written it doesn't sound like your husband is all that supportive; it's time to make your needs known and let him know that he will need to prioritize you and your relationship and your new baby.

This is YOUR marital home.  YOU pick the room you want as your nursery and inform your old assed DH (my DW and I have the same age difference that you and your DH have btw) that he and his prior relationship children will not detract from  your experience as a first time mom nor from the love and support that both you and DH will give to your child.

If DH so much as twitches in supporting you in this then  you move out, get an apartment and have your child without him.  Move out of state before the baby is born and nail his ass to the CS wall until he is pushing 60.

He in all likelihood won't make any effort to see your baby since you will not be there to care for him, his prior relationship breeding experiments and the baby. 

I have never understood either side of the first baby together chrisis while one or both spouses have spawned before.  This is your first baby together and you and the baby should have your DH's focus. The prior 5 are not young children. Except for the pre teen they are all in their mid teens.  

I have no BKs.  But I have always been all-in in raising my SS with my bride.  We met when SS-27 was 15mos old and married the week before he turned 2yo.  I have excitedly experienced nearly every first with my wife regarding our son (He assked me adopt him when he was 22. We made that happen) and even changed my fair share of diapers, got up repeatedly in the middle of the night to give him nebulizer treatments and alternating Children's Tylenol and Children's Advil alternating with his mom, attended every parent teacher conference, school event, concert, sports event, etc, etc, etc.....

The fact that he was not my BK did not impact my participation and IMHO that fact that your baby is your DH's 6th should make no difference in his participation with you in celebrating this baby as your first together.  He should be as commited and contributing just as much with #6 as he should have contributed to #'s 1-5. Even more. The prorr 5 have all had their turn at being infants and should not be allowed to interfere in your baby's turn. DH needs to be the one to have clarity on this.

Good luck and congratulations on the baby.

My guess is that he wanted you to get pregnant so you'd stick around.  But don't - 5 stepkids is about 4 too many.

He already has 5 kids (???!!!!!) and wanted 6th child yet he has zero interest in your pregnancy. What a loser. 

If you haven’t said anything about his daughter’s new room, you need to. Where is your baby supposed to sleep? Even if you kept them in your room for the first 6 months - 1 year, where does baby go after that?

If you haven’t spoken up, please do. And if you decide to stay with this man, please take all the new furniture & put it in the basement, move the SD’s back into the room together, and make your baby a nursery. He has 5 kids, some of them need to share.

If he really can’t be bothered though, take your baby & leave. 5 skids, omg. You’d think he’d be kissing your feet for putting up with that amount of drama. 

So... divorce him then. I'm usually an advocate for keeping families together/maintaining family values but...

I have a hard enough time allowing one child that isn't mine in my home. You are forced to allow 5. If you don't like them, take solice in knowing that your revenge will be the reason that they don't all get brand new cars at 16. Hit him up for spousal support and child support. He deserves to be f'd over with his treatment of you. Maybe he'll learn this time? 

5 step kids!!!! Damn!!! How are you maintaining your sanity? Having two was bad enough for me to leave and not look back. I left my DH and have no regrets. I'm now seeing a child free man and life is sooooooo much better. The first few months were hard but once you get passed that you will be so much better off. You only have one life. Don't waste it!

Why the holy f*ck would you get with a "man" that is that old, with that many kids, one of whom is an "affair baby"? First of all, gross. I'm not passing judgement on you, I'm passing it on him. 

So now he's knocked you up, because he obviously cannot be bothered to use protection, and you're shocked that he doesn't care? This may be your first rodeo, but it isn't his. And my guess is that he's burnt out on the whole "pregnancy" thing. 

Leave him. Like, RUN. 

Im doing it with 5 total sk, 3 full time and 1 part time and 1 grown and doesnt live with us and one grandchild living here as well at 47 years old and some days I want to just keep driving far far away. The chaos that one of them causes daily causes so much mental stress its insane. I will pray for your situation and that you make the best decision for YOU and your baby.