So you have a rental property that you own and she wishes to buy you out. There is only $200,000 in equity in the property.
Regardless that the property may be worth $500,000, the mortgage company owns $300,000 worth of that property, and you both, jointly own $200,000 of the property, or the amount of equity that exists
Therefore, as far as assets go, you each have entitlement to $100,000 of that equity, given a 50/50 split of matrimonial property
so, in order for her to buy you out, your interest in the home is only worth your $100,000 share of the equity so she'd have to give you $100,000
If you sold the property for $500,000, once the mortgage company is paid the $300,000 owed, the amount leftover, or $200,000 is what you both own
So she would not be paying you $250,000 as together, you only own $200,000 of the property, the bank owns the other $300,000
So if she buys you out, she gives you the $100,000, which is your half of the equity, and then she would sign a release, releasing you from your obligation on the $300,000 mortgage
Please let me know if you require any clarifcation
I know that there have been some issues with the chat interface so I switched the format just in case you weren't able to see my response. We can continue chatting here as much as you require.