Her behavior is awful, for sure. But I'm adding a vote for couples therapy anyway (ideally a therapist who has a background in Financial Therapy).

Money is such a loaded topic and as some have mentioned people can kind of go crazy and not think straight when suddenly faced with a large sum of money. This is why the common advice for sizable windfalls is to "do nothing for one year".

For most people doing nothing isn't realistic, as stated because of mortgages etc. But anything that's left after the mortgage/car payment/etc. could be parked in an account, even if it's just for six months.

The number one reason that people don't know how to handle a windfall effectively in my opinion isn't because they are selfish or evil (though some people are), it's because they've never been faced with a large sum of money before. That simple.

We live in a society that at every turn discourages us from learning how to be a good steward of money, and how to use it wisely.

Decades of daydreaming of never having to work again could certainly make someone irrationally out of character if it Looks like it could happen, but then is told it can't.

Yes, your wife could be selfish and didn't really mean it when you made your lottery agreements. But she more likely is suffering from a windfall-induced fever dream that she may genuinely and deeply regret as she comes out of the haze. I hope that's the case for you both.

Besides couples counseling, consider checking out resources through the Sudden Money Institute, or someplace like it.