Sounds like a complicated situation for sure. Without having first hand experience in your exact situation, from what I read here I might be inclined to try the following:
1. Grab a bottle of bourbon, deer sausage and crackers and stop by their camp. Even though I don’t feel like I’m “in the wrong” (so to speak) I would fall on the sword and apologize for not touching base with them about driving in on the access road. I would also ask for their help in identifying any trespassers or suspicious activity after explaining what mess someone created for you. Ultimately I think I’d try and repair the relationship (and maybe even improve it from what it was) to start.
After reading all of the comments there is some really good advice and a few things to consider. Besides the cost of the bourbon I dont know how you could go wrong with #1 from above.