My condolences....

I have no children either and no neices or nephews. My grandmother started me on Genealogy when I was a teen but none of her children care and none of her grandkids care about it but me. Sometimes I wonder why I do this but hope in the future one of my cousins kids will care.

I'm getting things together and will leave my stuff to the County Genealogical Society in the local Library where most of my family lived for generations.

I have my grandmothers originally-researched family tree, which over the years I have transferred from one program to another as computer software has changed, but I leave it as it is as a tribute to the work she did herself.

I think you should take time to grieve and then slowly start a new tree that you feel confident is well researched. Leave the old one as a record and for reminders. Your sourced tree can easily be separated into families via gedcom sorting anytime you need.

Enjoy the hobby you shared with your mother.