This is a long and complicated question. In general, your assets would be secure. However, you would want to be cautious with joint bank accounts and joint assets, including joint tax returns. I suggest you meet with a family law attorney to discuss this issue in detail.
This is an answer to a legal question posted on AVVO with limited facts and should not be construed as creating an attorney client relationship.
In most situations, a new spouse's income won't be considered for child support purposes. However, joint assets can create the possibility that you could be faced with a lien in later situation if he was ever to get behind on support.
A prenup might be something to consider, but you may also want to keep separate accounts and such to avoid the possibility of future liens or bank account seizures (especially if she has signed up for services at the prosecutor's IV-D child support office). There's a lot that can go into this decision and I'd be happy to discuss it with you further.
While I really do try to be as helpful as possible, you have to remember that every legal situation is unique, and that just because I offer you a general (or even specific) answer to your question, you and I do not have an attorney/client relationship.