peak current when i open the switch on LEDs

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that's good proposal, can you please propose a zener ? i did not find a zener with high voltage,
thanks
 

I did propose a string of zeners, so you need more than one. If you use 1W zeners, I would use them with a large safety margin, say no more than 0,2-0,3 W each, or less.

Let's say you set the zener voltage to 200V @20mA = 4W. 4/0,2=20 zeners, 200V/20 =10V for each zener. Remember to let each zener have some air around it, for cooling.
 

You could just use a current limiter on your switching transistor, as shown below. D5 and V2 on the right mimic your LED string. Q1 is the switching transistor. Q2 and R4 provide current limiting.

On the graph, the red line is without current limiting, the green line is with it.

 

that's a good proposal Godfreyl, i will implement it in the design,
in the meantime, i changed the position of C4, and it is connected throught LEDs, ( between R4 and the collector on the transistor), and i added a small 100nF/400V between the + and - of the bridge to avoide capacitive coupling between TOP and BOTTOM layer when the transistor is OFF,
 

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