Car dying when the lights are turned on?

generally, it sounds like your ign/coil is losing power probably under 4v once you get the headlights on.

so, you need to go through all of the connections to the headlights and relays. a bad connection will suck away power. probably not enough to shut you all the way down though.

sounds like a short somewhere, where the + is getting to ground. most likely in the headlight switch itself or a frayed wire or in one of the headlight relays.

best bet is to number one, check all the wires for any places where the insulation is gone
after that get a switch and relays from a salvage yard and swap them in
you will find the culprit