Are they indoors? If so the outside temperature doesn't seem relevant. Or are they outside? In which case what is the reflective stuff and light bulb?

They are in a greenhouse in a raised bed.

Not sure where you are but if you seem to think you need to plant in February i assume you are in a warmer climate than me. perhaps zone 6 or 7? Here is zone 5a i need to plant them at the end of March for them to do well. They prefer cooler conditions and in my dry climate with intense sunlight they do best in partial shade. I'm pretty sure peas would do terrible in a greenhouse since i feel like their leaves do not like to "sweat". Peas generally do terrible in summer when it gets hot. I have a few special varieties of peas that do okay in summer heat that are part of my pea breeding patch. Vireschens Mutante (from the german seed bank), Mummy-pea, Mummy White, Salmon-flowered, and Biskopens (aka. Sweedish Red). But none of these are all that edible, they are more starchy soup peas. Still they may help me breed a better pea for summer temps eventually.

Well I had quite the harvest before it got way too hot and they died.

Peas are one of my favorites but cannot handle the heat. A very short lived crop even in MI.