I think the trick is going to be to teach him to self-comfort, so that when he wakes up, he is able to get back to sleep without relying on you for this. It might be best to start with naps and then move on to night time. If he is currently nursing to sleep, I'd stop doing that right away. The goal is to put him in bed awake, but calm (will he take a pacifier, or does he like to be swaddled? That may help). He may fuss a little bit, but just let him do this in order to settle himself down. If he starts to cry, you can go in, quietly place your hand on him, say, "Shh-shh-shh" (but don't talk to him or pick him up). Once he is calm again, leave the room. He will figure it out, but it will take a few days. The other thing I would do is put him down for the night REALLY early - like 6pm. He will probably sleep a lot better going to bed at that hour. I know it sounds crazy, but try it. Put him down awake, but calm.
The other thing is, I'd very quickly try to transition him to sleeping in another room. Trust me, if he cries at night, you WILL hear him. But babies sleeping on their own make a lot of noise, and often times will even make crying sounds in their sleep. They will quickly quiet down again if you leave them be (because they're not actually awake, just restless in their sleep), but if they're sleeping right next to you, it's impossible to ignore the noise. You'll both sleep better if he's sleeping in the next room. I don't know if you want to try all of this cold turkey or gradually, but he's still young enough that it won't be too hard of a transition, probably. Good luck!