‘I own a house with my x-wife. Our daughter and her family now live in our house. If I die, who would get my half of the house? My x-wife and I are both remarried now.’
Unfortunately, there is not nearly enough information to answer this question. What would happen will be governed by a combination of your divorce decree, your wills (if any) and whether you are in a community property or a separate property state.
A more important question is, what would you *like* to have happen? Figure that out, then have a local attorney review your situation, and make recommendations as to what, if anything, you need to do to make it happen.