E.D.
I think you will just have to make the leap and put him in his own bed. At 5, it will take awhile for him to adjust to sleeping alone, but he needs to learn to do it. Does he have a bed of his own? Maybe get him some cool new sheets, a new comforter, a nightlight, anything to get him interested in going in there. Let him sleep with as many stuffed things as he wants (my 5 year old has a whole bunch of pals in his bed!). Do you have a bedtime routine? If not, start one, and follow it every night. Help him get sleepy in his bed, and then leave. If he gets up, bring him back to bed. You may have to do this a lot. I wouldn't recommend staying with him till he goes to sleep. We got into that trap when my son was around 3, and one of us would end up falling asleep on the floor! Well, when I was about 7 months pregnant, this was a bit inconvenient!
Once you decide to do this, stick with it! Don't back down. Just keep thinking about what a great night's sleep you'll have finally after 5 years!
Good luck!