M.M.
You need to get your life back. You will be so happy you did, but it won't be easy. The only thing that worked for my son was letting him cry. I know some parents think this is the worst thing you can do to a child. But we had to do it. We tried all the "transitional" methods -- sitting in a chair across the room for example -- and nothing worked.
So, I gave him about a week's notice that I would not be laying in/sitting by his bed with him anymore. We talked about it EXTENSIVELY so that he understood what was going to happen. We follow a very predictable routine before bed (bath, books and milk/pretzels, brush teeth, one more book, snuggle in chair together for no more than five minutes, then he gets in his bed). We had the routine well set before the change of us not staying with him til he fell asleep.
The first night, he screamed for about two hours, pounded on the door, told me how mad he was at me. It was the worst two hours of my life. The second night, he cried for about 10 minutes. The third night, he just gave a single protesting yell and fell right to sleep. At this point, he will occasionally cry for about a minute at most, then he's done for the night.
ETA: He was around 2 and a half when we did this.
Good luck!