An orbital collision would not cause an object to change direction 90 degrees. Satellites are not billiard balls. They are traveling at ten thousand miles per hour plus. Collisions at that speed result in two debris clouds that are largely traveling in approximately the same direction as before.

I would hazard a guess that you saw two objects that appeared to cross paths at the time one was disappearing and the other was appearing. Could be planes or satellites. Both can abruptly appear or disappear as they enter or exit shadow, or as they turn and reflect light in a different direction.