Estate Law Questions? Ask an Estate Lawyer.
How the trust fund may be used and apportioned must be done in accordance with the language of the trust. If you want some of the $ in the trust to pay attorney's fees, but many trust funds include language that limits the funds to be used only for the "welfare, education, healthcare, and maintenance" of the beneficiaries. That would preclude the trust fund paying attorney's fees. If this is an estate/probate issue, however, funds in the estate can be used for attorney's fees...
It's difficult to tell whether she is saying no because of the language of the trust (likely advised by her attorney) or if she just does not want to settle with you at all. I'm sure the settlement offer you made is fair, but for whatever reason, she doesn't see it that way. I would assume your next step is mediation.
If you have hired an attorney, continue working with him or her. You're likely in good hands, and this matter will eventually get resolved, even if it takes a while.