Steering Wheel Vibrate problems of the 2017 Dodge Grand Caravan

I drive a 2017 Dodge Grand Caravan. Last week, as I was driving my children to their grandmothers house, I noticed the steering wheel shaking. I regained control and made it to my moms house and dropped off the children. As I left her house and made it back to the road, the van became hard to steer. It started jerking to one side and wobbling. I called the dealership where I purchased my van and was told to bring it in immediately. The day after bringing the van in, I returned to dealership and they showed me what was wrong with the van. It was lifted up into the air and I was showed that the rear axle on the driver side had been broken. There was 2 mechanics there and one suggested that I had been in a collision or hit a big pothole. The other said that it couldn't have been a driver error because of the way the break on the axle was bent as well as the lack of any scratches or damage to any other area of the van. My tires and rims show no damage, and the undercarriage of the van also shows no sign of hitting a pothole, as there are no scratches anywhere under the van. One of the mechanics said it could have been something wrong with the axle because of the bent way it was broken and he also noticed that it showed signs of it being already cracked because the metal appeared to be old on one spot and fresh on another. I highly deny hitting anything like a pot hole or having been in a collision there is absolutely no damage to any part of my vehicle save the broken axle.