I drove truck for 17 years, and I have had a 5er for 3 years. I have never dropped a trailer. After you back into the hitch, get out and look at the connection before you move. No exceptions. That will avoid "high hitching", hitches not locked, etc. I also do not do a pull test. I do a visual inspection.
This doesn't have to happen, but it does take a little extra effort on your part. Literally, it takes 10 seconds. Also, you might need a flashlight to be able to see the connection good.
I am sorry you have to go through this, but if you learn from it and no one got hurt, it isn't all bad.