I have a few other words for people like that, the most polite one is acquaintance, not friend.
I have made a veritable plethora of acquaintances in my many years, and, sadly, only a couple "friends". Trouble with that is that one is passed now and the other is on his way. I've been working at becoming a hermit all my life. Looks like now, I'm about to graduate.
Anyway, I digress. It seems that anyone in this hobby will have a story like this. It's not just pertaining to this one, but this hobby hinges on two things that apparently go hand in hand. Greed and secrets.
If it helps any, I'll tell of a time when I turned the tables on one sonofadigger (I wonder how many times I can refer to this name without getting slapped upside the head?

).
This "friend" of mine, that I met while detecting, (just wandered up to me and started hunting nearby and then struck up a conversation). I was at a public spot and so I didn't care. What he didn't know was that I'd been around this hobby a very long time and recognized a con coming. Sure enough, he invited me to go to a couple of his "honey holes". I said, sure. Over the next week he took me to 3 public school grounds, explaining that the section we were hunting were very, very special and his research had proven their worth! He showed me pictures of some of the WONDERFUL finds!
Of course, the finds were very few and far between now due to his excellent skills. But, there absolutely would still be stuff to find yet.
Nothing.
Then he took me to an old 50's house where he had exclusive permission. Again, nothing. But he strongly hinted that I should offer the next spot, just to be fair.
I did, I told him of a WONDERFUL site that I had just begun to hunt as I had only recently gotten permission to hunt. It was still a bit too early in the year to hunt it as it was still overgrown. I showed him a couple finds I had "found there". He was literally chomping at the bit!!!
I set up a time to go there on a Sun morn. When I called up to set up a time, on Sat night, his wife answered and said he was out doing an overnight detecting with some of his buddies.
I drove over to the spot an observed from a long ways that sure enough, there was his car and several others. There was also the flashing of lights as they bobbed in an out of the trees.
Of course, this "site" of mine was never cleared for a hunt. Not by me nor anyone else. I had permission, just not until the fall. Someone called the police and complained. (No, wasn't me. LOL )
Anyway, I hadn't heard from him except for him to tell me that he had to beg off our hunt the next day. Two weeks went by. I called. His wife said oh he won't be detecting for a while. He's in the hospital with a very bad case of poison oak.
Well, I did say it was overgrown, just not with what. LOL
Don't let that guy spoil it for you. Move on, live and learn.
HH!