Questions: What should I have done differently EVERYTHING!!!!

You will have continued troubles for sure. You have apparently condoned their trespassing and misuse of your property for some time now so you basically created this monster.

You can never give a trespasser any chances,period. I cant believe you let them stay. That guy was laughing big time at you. When I run into a trespasser on my land they leave thinking they may have just met the devil himself. As you found out,they will lie right to your face.