Is it possible for one to be on depression for 20years, while working and do buisness as usual on working hours? then crumble only after work?

Yes it is.: Yes it is. Sometimes people's major sense of identity & self-esteem can be through their work. Being productive & working distracts them from their pain. They are able to interact with others. However, often when one goes home after work - they are no long busy, distracted & interacting. This quietude allows their sadness to seep out. They may feel empty & lonely. Sometimes contending with >>.