Greetings. The answer is that the ex wife cannot go after your property, unless it is purchased with money from the marriage with ex wife and ex-husband. Some people remarry before the finances of their first marriage are resolved. She is not entitled to your 401k nor will you have to pay her child support (directly). Now, you may end up finding that your new spouse owes her a lot of money and you will be spending your money on his children, but that is one of the possibilities you are facing.
As far as the child exemption on the tax returns, yes, if either parent has the child even one more overnight than the other, they can claim the child on their taxes. Your husband-to-be should make this a negotiating point. His recourse is to ask the court to grant him the exemption.
I assume that your husband-to-be is in court proceedings since he is divorced and that is the only way to keep alimony and equitable distribution claims open. If you move in together and get married, you decrease (hypothetically) how much money he will need on a monthly basis to live, which may increase his alimony obligations.
My advice is to follow your heart, but when in doubt, wait it out! If I were you, I would wait for a final resolution of the financial issues. Best of luck.
Janet L. Fritts
Attorney with Rosen Divorce
4101 Lake Boone Trail, Suite 500
Raleigh, North Carolina 27607
The response posted above is based upon the limited factual information made available and is not intended as a full and complete response to the question. The only reliable manner to obtain complete and adequate legal advice is to consult with an attorney, fully explain your situation, and allow the attorney sufficient opportunity to research the applicable law and facts required to render an accurate opinion. The basic information provided above is intended as a public service but a full discussion with an attorney should be undertaken before taking any action.