If she’s rich and married a successful tech founder, I don’t understand why she didn’t get a lawyer to draft these investment papers to keep herself from getting fleeced. Like the amount she was dropping could probably have been recouped from a buyout without much fuss if the contracts were a bit more assertive.
It's not a legal issue. If you invest your money in failed businesses, you lose. There is no legal machinations that will help.
As an angel, you do not get to set weird terms for your 10k check. The startup is raising on standard paper (these days almost always a SAFE) and you take them.
But no terms are going to save you from the reality that a failing startup that needs to raise more money will have to accept dilutive terms. You might be able to restrict it, but the alternative is that they can’t raise at all and shut down.