Your great-aunt was a good person. I also respect her. Do you live in the house?
My brother and I had to defend Dad's interest in a similar dispute over the house I now live in. His ex girlfriend wanted the whole house when she was entitled to half of it. The dispute was 2 1/2 years long. We won because the evidence I had carefully gathered revealed she had spun a web of lies and had agreed that she was entitled to half. I'll never forget our moment of triumph and how the mediator (an off-duty judge) shook my hand and said "well done." He also decided she had to pay our costs, which I received in bricks and mortar, not money, but that's ok. We had an excellent but expensive barrister who talked us out of taking the more costly actions.
It was not easy while greiving and while writing a thesis and while working full time. No wonder I became sick. On the other hand it showed me how strong i am.