Ahh, I see what your doing. Use an off the shelf zerocrossing SSR (solid state relay) switched on by the PIC at any time (timing not critical). Turning off the mechanical relay would not be zerocrossing though, unless you turned on the SSR 1st just before again, and then that might be tricky because there would be no voltage across the SSR for it to turn on (shorted by the SSR). It would turn on just as the relay was opening (voltage appearing across the contacts), which might work, and then zerocross turnoff with the SSR