I think MI is a 50/50 state. So, when you get divorced she gets half of everything gained in the marriage, that includes pensions and bank accounts solely in your name or solely in her name with the exception of inheritances where the funds were kept completely separate.
If you are going to be making payments to her for a specified time, or in perpetuity, that’s alimony. I’m not sure how they figure alimony, but if it’s based on your income, then maybe your social security income counts in the equation. I don’t know if social security can be garnished? Maybe that’s what she is talking about to guarantee she gets her money. That’s assuming she deserves the money. If she is just trying to take as much as she can, well, the law probably is on your side if she is asking/demanding ridiculous things.
A mediator can help, or judge will decide.