Separation agreement questions after the fact

I have what I think is a unique situation and question. Due to serious medical issues that arose during our divorce and a need to qualify for medicaid, my ex-wife signed a separation agreement where she relinquished all rights/claims to any of our marital assets, my pension & 401K, our house, etc. We both had our own legal representation and there was additionally another attorney in the middle with a specialty in elder-care law and medicaid matters. She was advised that the above was necessary in order to legally qualify for medicaid and SSI. Outside of the agreement we verbally agreed that I would continue to help her financially as I was able, which I still do.
Whenever we have a disagreement/dispute she threatens to go to another attorney and file to have the original separation agreement re-written…can she do this?
The above (sep agreement & divorce) took place between 2004-2006.

Also, if I re-marry what happens if she does in-fact tries to get the above changed?

Thank you,
SJ

You are not legally bound to support her. She may try and have the separation agreement overturned, but in my opinion such an attempt would not be successful.