Well, if it's affecting your mental health you should just file it and get it over with

Eventually, they will find out and make you pay it back

If you're nice and apologetic, they'll almost certainly give you a realistic and decent payment plan as long as you still have an income

They don't want to throw you in jail because then they can't get your tax money. Their goal is to get everything that you owe them

Worst case you can declare bankruptcy if you don't want to pay it when they chase after you at the cost of your credit score being destroyed for years and year