Are details of a trust confidential and can the executrix provide info to confused former family member?

I recently became executrix after my sibling who was executor died. I have one area that is causing me issues and I need advice. My father set up for a family property property that has been passed down, to be given to all 3 of us kids - no persturpies to others, it is just left to us 3. Now one of us as has died leaving two. Legally it will pass to us two. However....and here is the crux of the problem.....the property bills (power, taxes, upkeep) has been paid for equally between the 3 of us for years (about $400 per year each), our dad has been unwilling to give it to us before death due to vast increase in taxes. Ok, so my brother died 2 years ago and his wife keeps paying his share of upkeep -not knowing that she will not inherit it. And she has been the one keeping the books all these years as her husband was Executor. Now that I am Executrix I told my dad that he needed to talk to her and tell her of the situation and take back all the bills and pay them himself or he can bill us 2 remaining on his own. But that if he continued to allow her to pay and not inherit, he is opening his Trust up to a lawsuit upon his death. He talked to her but only to have the bills transferred to me. :( He refuses to address it and says it will be up to me and my remaining brother, when he passes, to decide if we want to "cut her out" or give her my deceased brothers portion. :( I will add he has been insanely generous with her and all her kids in the Trust and they are likely getting more than my brother and I because her husband was the favorite (lest you think they will be out in the cold, she is a lawyer and they are all very well off). He says he wants us all to get along and be harmonious but this is setting me up for failure. Honestly, I refuse to bill her for the property and we owe her for about $800 each for what she has overpaid the last two years since my brothers death. How do I explain when she does not get a bill from me? CAN I explain it to her? Is that proper or legal? I am caught between a rock and a hard place because my dad won't take care of it.