You cannot. As a child ( and we all are children until our parents have died ) you have to cope with parental behaviour like this. Be calm, tolerant and try not re-educate parents. When things are too bad leave them alone in their mood. Do not offer yourself as a litter bin of their emotions, this isn't loving your parents, this is garbage collection. Do not mistake one for the other. Parents have sometimes encroaching habits with their children. They do not mean to be that, but it simply happens. it is your duty to remind them of this civilised fringe of intrusion we all are keen to respect usually. They will not understand in most cases as far as my experience goes. Nevertheless keep a relaxed stance but be adamant not to be a litter bin of parental over care.