Wait a minute, Darrin,
You mentioned, Triac. All along we thought that you were PWM'ing from a DC supply.
A TRIAC works like a latch, since once it is triggered, then it conducts and stays-on until the current through it drops very low (when the mains voltage crosses 0V for resistive loads), when it turns itself off. The TRIAC must be triggered for each 1/2 cycle of the mains. You don't need a PWM circuit, the TRIAC does it. All that you need is a circuit that is syncronized to the mains frequency, and gives a short pulse to the TRIAC's opto with a time delay from when the mains voltage crosses 0V.
With a short time delay, the TRIAC is turned-on early for each 1/2 cycle, and therefore gives nearly full power to the load. With a long time delay, the TRIAC is turned-on late for each 1/2 cycle, almost when the TRIAC will turn itself off anyway, and therefore gives a very low power to the load. The time delay must not exceed the time of 1/2 cycle of the mains frequency.
Recently, 2 other posts discussed "lamp dimmers", with circuits to do this. I would find them for you, but lately this site's navigation is very slow.