To move forward it is not necessary to forget, it can also be done by carrying in one's heart a memory that gives strength and to cling to from time to time.
But, how easy is this to do for a 6 year old and then, how much damage is done in the time it takes to learn? Society doesn't have a good mechanism for dealing with these kinds of things, especially now that family ties are even weaker.
Of course you're right, for a six-year-old I'd say it's almost impossible... he'll grow up and he'll need it for the future, obviously when you're a child, everything is lived differently and has a different meaning.
I agree with you that in today's society family ties are perhaps too weak, I believe that we should do so to make them stronger.
However, although I don't know you much, I believe in you and I know that whatever you do will always be for the best of your family and this is important.