I think you´d better start with something less dangerous, say creating 24V from 48V or similar, it seems to me that you don´t yet have enough experience to be playing with mains directly. The danger is not just in the high potential that could kill you, also there is a high risk of fire and exploding components if you don´t do stuff right.
What I meant was, that to turn on a mosfet, you need around 12 volts more on gate than there is on source. The way you have it now, you have ~320V at the source, and something like 5 or 10V at the gate. That makes a nice -310V between source and gate, and that makes the mosfet blow up in a spectacular fashion, as the max permissible voltage is +/-20V. You need to use a proper driver arrangement to achieve normal operation, for example through an optocoupler.