If I were in your shoes, I would do some research on the matter of the estate and how this would be divided up when there is a second wife in the picture. Each state could be different in the way they handle such things. In my state, the current widow gets everything and it would be up to her if she wanted to give something to your children....but I seriously doubt she would be kind enough to do so. Unless your h stipulates in a will that he wants a certain portion of his estate to go to his children, the estate most likely will go to her. The current Mrs. Beret can contest a will until the cows come home. If the will is done properly, it will be difficult to get it overturned in court and that will cost a lot of money and time, which she doesn't have much of either, i.e., money.
Also, if he's paying into Social Security or did pay into it, your children may qualify for a monthly payment until they are either 18 or 21. Again, something you need to check into, especially the age limit.
As for the debts...they are hers to deal with! Don't be surprised that if he passes away, that she doesn't come calling wanting you and your children to help pay for the funeral expenses. Been there, done that w/my former xfil who was on his 5th wife at the time of his death. Fifth wife looks to his two sons to pay the funeral expenses because they were separated and he was living w/the current girlfriend.
I may be totally wrong, but I don't think your xh is going to cross over any time soon. Unless you've seen his medical documentation, I would sit back and just observe. It may or may not be a serious matter...but time will tell, just as the medical documentation will tell what's what. I wouldn't be too concerned until everything has settled down.
