The Terminator's Future Can Never Happen

I'm looking at The Terminator and Terminator 2: Judgement Day. Now, I'm not saying it can't happen in the real world. I'm saying it can't happen within the world of the movie. In Terminator we are told that, Skynet sends a Terminator back in time to kill Sarah Conner so her son John Conner can never be born. So, John Conner sends Kyle Reese back in time to keep Sarah from dying. And in Terminator 2: Judgement Day, we learn Skynet actually sent TWO Terminators back in time to kill Sarah Conner, the T-800 in the first movie and the T-1000 in the second movie, so John Canner sent a THIRD Terminator back in time, this one was programmed to keep Sarah and John conner from being killed by the T-1000. During the movie, the Terminator from the first movie's arm is destroyed and so is the T-1000, and the good Terminator explains that he also has to be destroyed as no part of a Terminator can exist in the past otherwise Skynet will be formed and the Terminators will be made, and it will end humanity. So, the good Terminator sacrifices himself. So, do explain how the bad future happens if there is no trace of the Terminator left? I know Terminator 3 explains it but either way it just doesn't work out the future in the Terminator cannot exist