I feel for you so much and I'd like to help you. I've been through similar and I have children as well.
You have handled this perfectly and huge shout out to your brother who totally has your back and huge emotional intelligence to offer to tell people so you don't have to.
Your husband is showing his real character even more that he's not asked about his child or unborn baby.
You will be on a wave of adrenaline and support but be aware that a crash may come later along with sadness at the reality of what has happened, what is happening now and what the future will now be. Don't rush to get over or past anything. Take the time you need.
I am 16 months on since we split and four months since we divorced but my now ex h continues to do things that is causing me immense pain. It is a long process so just be aware.
I truly wish I'd posted when what happened to me happened but I chose to stay then and to be honest didn't want a million LTB, you're a fool for staying etc comments. The women on here are mostly incredible and there will always be someone to help with practical advice, emotional support and things to fantasise about doing to him that will make you laugh. If it comes, take advantage of his guilt to get as much out of him as you can but the reality is, finances, housing, access to their father will all be decided by a Judge. But if he'll give you stuff now, take it.