Didier: Wow, what a tough time for you. I do have one suggestion and it is antidepressants. I work in the mental health field (research, I am not a clinical person) and one thing that is very exciting is the profusion of new antidepression medications coming on the market. They are no longer sleep inducing & most have few side effects. Some target anxiety, some target depression.
You sound depressed in your posting and it would be amazing if you were not given the heavy burden you are dealing with. Situational depression can be helped by many of the new meds. Many of my friends have had to deal with aging parents and fatal diseases in the last 2-3 years and I have been surprised at how many get very depressed in the process. One friend finally took several months off from work just to deal with his mother's situation. He took antidepressants too. Your reaction is fairly typical. However, You cannot keep helping your parents if you don't take care of yourself. Please think about seeing your primary health care doctor about antidepressants. They won't make you a happy go-lucky guy, but they will help you deal with anxiety and depression caused by the tough situation you are in. Good luck!