Desirousofchange is right in my opinion.
Memorize this line: "I know this is Jehovah's Organization, and I just accept the fact that there may be some things we have to wait on to understand completely. But I'm sure He will provide everything we need when "New Scrolls" are opened in the future. I appreciate your loving concern, but you brothers have totally over-reacted. I really thought you knew me better and had more confidence in me."
Don't worry about the blood issue with your kids as the Courts will issue a Court Order if it becomes necessary for an ill or injured child.
If your concern is for your children, the being close by them in case of a need for a blood transfusion would be the wisest choice, This more than likely will never happen, but if it did, this would be the time to make a stand. If she was awarded full custody, you may not even be aware of this need until it was too late.
Again, recant, and chant the "wait on Jehovah" until the zombies settle down a bit. Read up on Steven Hassans books, Combatting Cult Mind control and Freedom of mind as you need to learn what and when to say if anything at all.
There is nothing wrong with teaching your children how to think critically. See youtube videos on this if not familiar. Depending on the kids ages, you can use a proxy for their religion such as any major investment or decision that should be researched prior to a commitment. If smart and you word it correctly, they will understand that ANY MAJOR decision (including a beleif system) should be processed through "critical thinking" to make a wise decision. I know that this is down the road, but being right there with the kids is the most important thing at this time. You need to become an actor for a bit until these things settle down.
Hope all works out.
Also, if she moves out, makes you move out, and it looks like divorce you need to look online for some publications that the WTBTS has provided to JW parents that teach the kids to lie on the Stand to make them seem more main streamed. This would work well for you, if it goes there, when it comes to a reason that the kids should not be left to the wife due to the religion. I'm not sure of the name but feel that others here may be able to help with that.
Regards, and be sure to come here with your concerns and be sure to use "Private" browsing to prevent any software from tracking where you have been visiting. You need to think of this as war until proven otherwise.
NJY