Full-time cheapskate Spouse

My spouse is a cheapskate, it is gross, hideous, and most of all embarrassing. It is so bad that family on both sides tell me to put my foot down since children are involved. And even the children tell me to put my foot down. I don't know what to do. Partners cheapskate'ness is also starting to damage the marriage in very toxic ways due to the living conditions of it. It's also embarrassing to have any guest/s over, family or not.

What do I do? How do I handle this? What would you do?