It can be very tough taking care of your elderly parent(s) because they're usually infirm as well. If you're also holding a full-time job, the stresses combined can make you head towards a breakdown.

I guess there's no easy way to deal with nagging. I deal with it in different ways, depending on my mood. Sometimes, I just 'zone out' and practice selective deafness.

Other times, I'll just walk out of the room if I find that I'm reaching boiling point and about to burst.

Yet other times, I'll just playfully exclaim, 'Aiyoh!! Talk so much! My eardrums are about to burst already! Give your mouth a break, lah!'.

Caregivers have a very high possibility of getting stressed out. That's why there's this service provided by various nursing homes called 'Respite Care' whereby for a fixed period, the family members can leave their elderly and sick at the home, while they take a much needed break or vacation. This is a temporary arrangement for a fixed period of time and when they return on their vacation / break, they'll have to bring the elderly and sick home again.
Sounds like you might be facing Caregiver Stress. Various hospitals have support groups for caregivers like you. They meet regularly to share their frustrations, share coping techniques, and make friends with other people who are caught in similar situations. Find out from your hospital / polyclinic if there's such a support group you can turn to. Don't underestimate the role they can play - sometimes, it really helps to talk about your frustrations, and have a whole group of people empathise.
I certainly hope that you have help in taking care of your parents, especially if you're holding a full-time job. It's not an easy burden to shoulder, but I applaud you for choosing to take care of them at home, despite the difficulties you're facing.
