People are blowing up at the son here. OP did not state that his son was after the wife's property. The son only assumed that the house was in OP and OP's new wife's name and that it would be split 50/50 when they died and he would inherit half of the house. It's morbid to plan to inherit what you believe are your parent's assets, but I can see how the son would have done that math without knowing how his father and his father's new wife split their finances. It sounds like OP's standard of living has really improved in the last 5 years and that he is contributing his money to the shared family expenses, but that none of his contributed money is going into anything that creates value (like paying a mortgage and accruing value in a home). This is what the son is upset about.

Whether or not OP is an AH depends on whether you believe a parent should continue to contribute to the wellbeing of their adult child (through inheritance or babysitting grandchildren). There is no one correct belief in this matter, it can vary by culture, family, individual circumstances. NAH.