Switching Negative Half Cycle of AC With IRF9240 P-Channel MOSFET and PWM Control

I am facing a problem in switching the negative half cycle of a diodes output. Diode is connected in series with 230V AC supply. Load is a capacitor. I want to cut both sides od the negative half cycle symmetrically (symmetric angle control). For this i generated PWM signal using PIC. Gate signal is varied from -9V to 0. It is made possible by using the below circuit
Now the problem comes when i give this gate signal to P-channel MOSFET 9240. I give the negative half cycle wave from the diode to the drain and the source to the other end of AC line. When i switch ON supply to drain-source, gate voltage is level shifted down to become more negative and gate wave is inverted. How to tackle this problem... please help me.. its sooo urgent