Change the 0.1V to what you need. I don't know what current flows through your load so I just put a number. My circuit is only a guide and not a final circuit.
There could be a confusion about this feedback issue. Feedback in most cases is sampling of the output and feeding it back to the regulator for the purpose of controlling the output.
In other cases a certain state of the output is fed back for the purpose of protecting the circuit.
I assumed that your circuit is for the purpose of protecting your power supply and not for controlling the output voltage.
If you need to control your output voltage you cannot use an optocoupler because an optocoupler has only on or off state.
BTW, I read your previous thread about RL in an old inverter. It is common for engineers to use a resistor as a bobbin for winding a coil on it. The engineer uses a resistor which is the right physical size for the coil, the value of the resistor isn't important. 100 Ohm in parallel to less than 0.1 Ohm of the coil wire is insignificant.