I have been there, done that!! My oldest was almost 6 before we stopped laying down with her while she fell asleep. It was a long, sometimes painful process getting her to go to sleep on her own, but it was well worth it! She also would get up in the middle of the night to come to our bed (EVERY night for 5+ years!)
We found that once she was able to fall asleep on her own, the night visits got fewer and fewer and finally trickled off without us doing anything about that (I was no fan of getting up and putting her back in bed either, so we didn't).
We got her to sleep on her own by sitting on the side of her bed instead of laying down with her. We did each step for 2-3 nights (staying until she fell asleep): sit on side of bed (our side facing her), sit at end of bed (facing away from here on out), sit on stool at end of bed, then moved the stool about a foot each night toward the door until we were out in the hallway, then moved the stool down the hallway a foot at a time 'till we were out of site. The first 2-3 nights were pretty rough (crying, getting out of bed- we just calmly told her it was time to lie down & would gently put her back in bed with minimal interaction & no eye contact), but I was really surprised at how easily the 3rd or 4th night went. If you just remain calm and reassure him (minimally) the first night or two, he'll see that you're not leaving. You just have to keep your eye on the goal of someday soon being able to kiss him goodnight and walk out of the room.
I read that once children learn how to fall asleep on their own, the night wakings lessen because they're ok with being in their bed without you and can go back to sleep. It's shocking for them to go to sleep one way (with you there) and then wake up with a major change in the room (you're gone). I think the example I read was to imagine if you went to sleep in one room and woke up in another-- you wouldn't be able to get back to sleep either. Anyway, we found that was really true in our case and a few weeks after she started going to sleep on her own, she skipped waking up one night. Then a while later, she skipped waking up for 2 nights, and so on.
Please believe me when I say that I feel your pain! Just know that you really can get beyond this by being consistent & having resolve. Good luck!