I read through your posts,, dang tough deal for you and your friend. From your posts the landowner was playing the "rent game" with your friend.  You were shooting straight and being square with your friend.

Landowner's can be real lowlife's but do not let that reflect on you.

Don't continue to second guess whether your friend believes you or not. If he is as good a friend to you as you are to him,, he will absolutely know you didn't get in-between him and the land he had been renting. I bet that is what is bothering you? Worrying about whether your friend trusts and has enough faith in you as you have in him?

As a "test",, just reverse the situation,, if you were him, would you believe him if he came to you explained the situation and rented land you had historically rented?  From your post's I bet you would believe, accept, and understand his explanation.

Do give your friend the credit to accept your explanation by not continually second guessing,,"He said he believed me but I know deep down he will always wonder."

Your friend is having to choke down a "bitter pill" right now,, so give him credit and time to get that pill choked down. 

If he is as good a friend to you as you are to him,, he will get through this situation accepting, believing and knowing you would not rent ground away from him.

He was just played by a landowner.

just my 2 cents