It's nice to keep the memory alive as long as it doesn't hurt all the time. My dad passed away 5 1/2 years ago. My grieving phase lasted a few years but time will heal the pain.
When the family gets together we sometimes reminisce about dad and the 'good ole days.' It is unavoidable not to get wet eyes, but that is a natural and healthy reaction.
I like to think the loved ones who passed away are in a better place now. That thought helps.
Sending hugs to you for your Dad: I think my Dad would be quite happy to know what I'm planning in order to take care of Mom.