Does your son still take naps? Have you tried letting him sleep in his crib for naps, to start? Maybe you could lay down next to him on the floor while he tries this, or read to him, or play some special music when it is time for him to go to bed in his room/bed. I have tried all of these, they seem to help...
I don't agree that it is universally "bad" to have your son in your bed, but if it is interfering with either your or your husband's sleep or your intimacy as a couple, then there could be room for improvement...
My son sleeps in my bed occasionally (he is 2 1/2), but has liked his crib since he was really little. When he isn't feeling good, or if there is a stormy night, my son insists that he sleep with me, & that is OK with me. Dad sometimes just sleeps on the couch, so for us that works out fine. We have all learned to take care of ourselves when it comes to sleep, & for us that involves each of us having a couple different options for where we can sleep the best.
Another thing you could consider is to possibly have a place your son can sleep in your room, without having to be right in the bed with you; like a small futon near your bed, so he can hear you, reach out a hand to feel you (or a foot) & knows where you are. You could also try putting the futon (or a small airbed) in his room/by his crib for you to sleep on, so he can learn that he can be in his bed, but that Mom will still be near, & he can start getting more secure with being in his own space.
Crying it out is really hard, & I agree that most of the time it doesn't seem to intuitively make sense for parents to subject their kids to this. However, you don't have to be so extreme to let him cry it out without any sort of soothing or comforting. If he is crying, you can verbally let him know you are there, but limit picking him up or eye contact, so he knows that he is safe, you are listening, & if he really has a crisis you'll be there. This worked for my son. You'll know if it is a crisis, or not.
Just be prepared to think creatively & outside the "box", & you will figure out what works best for your family...like I suggested, perhaps with you sleeping in his space, to start.