I killed my lizard by starvation didnt I?

My poor lizard was 3 & 1\2 & I just found him dead as if midway through walking around a rock .He started only sleeping on his heatmat or at the cold end of his tank in April & wasn’t eating much food. I kept feeding him but the food would just go off so eventually I stopped feeding him every week but he shed his skin after this and seemed fine. At one point I turned his heating off coz he kept moving to the coolest area when I warmed him up. The room I had him in probably meant his tank was getting quite warm but I fed him rarely, i think he might have gone a month or more without eating. What I did was very wrong wasn’t it? I should have ensured he always had food and kept his environment alot more stable. I can't belive it i thougth he was ok and im so upset please tell me exactly what i needed to do for lizard.