“Speeding While Passing Help Please”

So here is the story. I was following a vehicle in an 80km/h zone for quite sometime the vehicle kept slowing to 70 then accelerating to 100. Finally saw a spot to pass safely and did. The oncoming traffic was a vehicle and an OPP cruiser behind. The OPP officer pulled me over saying they clocked the vehicle infront of me going 100 and got me doing 139 but there was a vehicle infront of the officer so i dont understand how they clocked anybody especially me with 2 cars blocking the cruiser. Regardless I know I was speeding I told the officer about the other vehicle etc. I also had a double whammy expired insurance card 10 days ago the officer also gave me a ticket for that. My problem is I had my child in the car with me it is -2C on this night and the officer took my keys with my window down and left me and my child for 20min in the freezing cold. Then came back with the tickets speeding of 40 over and the failure to produce insurance and then told me that they would be keeping my insurance card so I better put a new one in and now I am left with nothing at all. Not only am I very angry the officer made me and my child freeze but they took my keys which I havent heard of and kept my insurance. What if I got in an accident after this I now have nothing. I am wondering if I can fight this ticket because not only do I think I was not going the speed the officer said I believe it would be hard for them to get me with a dash mounted radar with 2 vehicles in the way and still have time to get the speed of all 3 vehicles like they claim. Is leaving me and my child in the cold some sort of human rights violation and is taking my keys allowed. If anybody can help or steer me in the right direction it would be greatly appreciated. I know my ticket was already reduced and they say they could have got me for stunt driving that is why I am not sure if I should just pay or fight my case. Thanks in advance