"All My Children" star Cameron Mathison has shared harrowing visuals of where his Altadena home once stood -- and now he’s revealing the full story of losing it in the raging Eaton Fire.

Cameron stopped by "TMZ Live" Wednesday amid all the devastation -- and his shock was clear, as he recalled seeing what started as a small glow in Eaton Canyon above L.A. Tuesday evening, only to return the next day to find his home reduced to nothing.

Cameron told us everything -- how he grabbed a few things to evacuate last night, and hit up his estranged wife’s place, before rushing back to save some sentimental stuff.

This morning, as fire coverage dominated TV news reports, Cameron couldn’t tell if any of the homes shown were his -- so he went back to check. What he found? His worst nightmare.

Cameron made it clear -- losing his home isn't just about the destruction, it's the years of love and painstaking detail he poured into it ... a feeling that’ll resonate with so many others affected by these devastating wildfires.