car over heated when electric fan didnt go on

driving home from school today i noticed my temp gauge going way up. its about 90* today. when i got home the factory gauge reached 270 just as i pulled into the driveway. i babied it home never reving above 2500 usually had it below 2000. when i got home i turned the engine off and then turned the key forward to see if the electric fan would go on. it didnt but i heard this other funny sound. opened the hood to find the coolant in the resovoir bubbling it was so hot. it began to pour out the overflow and its all over my driveway. i think the relay died. does anyone have a link to a good relay. i have a temp probe. the bottom of the relay has black burns on it and some of the plastic melted near the positive wire. i was thinking i could get one at radio shack but have no idea what to look for or what type of ratings they have. im sure its at least 30amps

the car wasnt making any funny sounds and idle was really smooth so im hoping i got lucky