How fast can a cat die from a black widow spider bite?

  My cat was playing with me, then laying on my lap 2 hours prior to me finding him laying on the cement in the garage looking very peacful. He was 7 years old, healthy and full of the devil. I am in shock. I have no idea what happened. He had urinated but know foaming at the mouth. Looked like he was sleeping, I kept calling to him waiting for him to perk his ear up or wag his tail. He sometimes likes to ignor you like he is playing.
GET HIM TO A VET NOW!! HE COULD HAVE GOTTEN INTO POISON! If he drank anti-freeze he could die REAL soon! Take him NOW !!!!!!!!!
He may have eaten something or licked something on the floor of the garage. I would take him to a vet.
Take the poor baby to the vet!