The Desoto Police Department posted an image to their Facebook page of the absolutely enormous python they found on I-35. If you're scared of snakes, have no fear -- this one was already dead.
Pythons aren't venomous. Instead, they're constrictors that kill their prey by wrapping themselves around it and squeezing it to death. They're still dangerous to humans, though. Pet pythons have killed their owners or their owner's children in the past.
Pythons aren't native to Texas, either. This snake is likely to have been someone's exotic pet that they irresponsibly released into the wild. The responsible way to get rid of a pet you no longer want is to bring it to a pet store or contact a rescue. Don't release it in the wild.