My girlfriend and myself just went through this ourselves with her cat of 16 years Knittnmom. When we knew the end was close the vet gave us some meds for his comfort and he died peacefully with us. Cherish the time you have left, they really are members of our family.
That’s our feeling, as well. And this cat is something special - she actually likes people. Makes it even harder to lose her, as she is a part of almost everything we do - gardening, playing music, watching tv - she participates in everything.