On a different note, I would look into the baneful magic section of this site… See what can dig up to fire back at him. Throw him some of its own shade. Plenty of curses and baneful spirits out there to play around with.
There are also rituals in NAP for exactly this kind of thing - returning curses back to the caster so it affects them, I believe it’s called occult Judo.
You could also tell him straight up to leave you the F alone… Make sure he understands exactly how you feel about him and the whole thing. Sometimes, the simplest solution is the best 
Barring that… It occurs to me that he may be spoofing that connection you feel to Lucifer. What if it’s just an egregor that he created to give you the impression that you have the big L on your side? Feeding your energy and hope into that thing would only strengthen it at that point… The more I think about it, the more likely that seems. I don’t know why nobody else has considered that… So I would look into this thread here:
One further note… I would assume this guy is already working with the dark forces. If they’re loyal to him, and I have to guess they are, because he sounds like he’s pretty skilled in all of this, you won’t be able to call upon them at all… Lucifer, Belial, anyone else that easily comes to mind, he’s likely already worked with extensively. Which is why I suggest looking into either more obscure spirits, entities of different pantheons (like voudun), or the more angelic forces (NAP) that could counteract his influence on you
Huh. As I was typing this, I suddenly got dizzy and out of breath, like I was about to pass out… Almost like someone was trying to prevent you from getting accurate outside help 
So… That kinda gives me the feeling I was correct in my assumption. Fuck that guy and his tricks, I hope my advice helps bring his little game crashing to the ground 