D.B.
First off, you are still in the hormonal phase, and you are exhausted from a newborn, let alone a fussy one. So you may be extra sensitive here. Try to give yourself a break.
Every 8 year old (and 6 and 12...) has problems with a new baby. Let's face it - newborns are a pain! They don't do much even on perfect days, and if they have colic or medical issues, it's worse. So the fact that your daughter is disappointed or irritated is not a reflection on your, your husband or this new baby.
It's okay for kids to experience disappointment sometimes - it's preparation for life. Sometimes we work so darn hard to make sure they are never unhappy, we actually deprive them of the chance to be disappointed and see that their world didn't end. That goes for new babies, rainy days, teachers/coaches who have policies every child might not agree with, friends who excel in a particular area, not getting everything on their Christmas list, not being able to ride a bike the first or 12th time, and so on. So your daughter is learning what every 8 year old should be starting to learn!
This is also a good head's up for her that having a baby at 15 or 18 is not going to be fun and games - it's a 24-hour job and some days are nightmares. I'm not saying to give her that talk now, but keep it in mind going forward as your little one gives her (and you) challenges. And there will come a time when your tween and teen daughter will annoy the little one, so it will be payback!
I do wonder why your daughter spends so little time with her father. If there's a problem there, that's one thing. If he's not interested, that's another problem. But if he's a decent father to her (as terrible as he was to you), it might be good to let her have more of a relationship with him and be less totally dependent on you. You are close, yes, but you are her parent and not her friend, so she needs to learn that for herself now and for her adult relationship with her own children. Her teen years will be terrible if she expects you to be her friend (when you need to rein her in a bit), and if she doesn't begin to separate and form more enduring friendships with peers.
I do think you can avoid including her in everything with the baby - she needs to do 8 year old things, with friends or her father or her stepfather. It's okay. You can also have her invite a friend over and you bake or make pizzas together - then if the baby is having a bad day or not napping, they have each other and you can direct from a distance.
It's hard to bond with a fussy baby when you have another child. Spend time with him alone if you can and stop worrying about your daughter every second. You didn't have a second child or even a spouse when you had your daughter, so you definitely established a closeness, but sometimes that's not always good. I think each of you has to find your own way here - she needs time without you, you need time without her, you both need time together without the baby (when he is with your new husband), and your and your husband need time alone when both kids are with a sitter.. Try to make those separate relationships happen without guilt.