These losses are especially galling because they are so unnecessary, just a tragic waste of human potential. How would you feel differently if your cousin were killed in a car accident or a meningitis infection? The suicide of a young person is just so illogical.
I suspect you will find that this experience will affect you for many years. Absolutely do find someone you can talk to about it or, perhaps, you do that online. Trying not to think about it and blocking the painful feelings, while sometimes a necessity for a short time, is not healthy.
Someone above suggested trying to be the best person you can be. I also say, since your cousin couldn't live a full life, let that be your reason to life a full one yourself, a long one, a healthy one, and a happy and successful one.
It always amazes me how many people settle for unhappiness. For all those who have gone before, for all those who couldn't live a full life, as living people it is our OBLIGATION to live as happily as possible. Anything less is a waste.
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A finger in every pie.