<human>: There is a guy I met at 15 years old, and we started off having a lot in common. He revealed he had a crush on me from the very beginning, and I made it clear early on that it wasn't going to happen and we should only be friends. At age 17, we experimented sexually for the first time...and have continued ever since. It's ongoing. I've never had a boyfriend (because I don't particularly care for a romantic relationship) and for the most part this is what works best for me.

I'm not a people person; I'm not a little miss sunshine and I can be a downright buzzkill. If I have to be around people 
for too long, I become a restless and insufferable grump. The 
idea of dating someone full time while working a full time job 
seems unthinkable to me. Too much work, to be completely 
honest. I'm in a bit of a rut though...as of late, I cannot stand to be around him anymore. I'm not sure what it is, but all of a sudden he's gained a "holier than thou" attitude and speaks to me in snarky, disrespectful ways. This was never a problem a year ago. 

We also have much less in common than we did as teens, but I suppose this is to be expected. He's into all kinds of drugs like adderall,roxies, and methamphetamine, and I'm not into any of that. I feel we are going in separate directions, and I wish to move on with my life without him. I have fears, however, that he will reveal things I've told him in confidence. My fetishes that aren't so common, things I've asked him to do, things like that. It would devastate me if these were shared with my family or someone else.

Normally I wouldn't have to worry about him doing this, but with his odd and narcissistic behavior as of late, I'm not sure if I could trust him anymore. 

What should I do?

Can you condense the text into a few key points?
<bot>: Ending a complicated friendship with a man I've had sexual relations with for years. Preventing him from telling private details.