J.T.
My daughter now almost 3 was nursed / co-slept until she was 2 and only this month has started sleeping through the night by herself.
It was a tough journey (she threw herself out if her crib at 18 mos. when I tried CIO) but in increments we made it...
First was stopping the night nursing then any milk, switched to water in a sippy. Then I stayed with her in her room next to her bed on a sofa. This step lasted a long time, gradually reducing the time I was holding her hand, but eventually she was able to sleep in her bed with me on the sofa, not touching her, just there.
Now she goes quietly to sleep on her own (very recent development) and I get to sleep with my snoring husband ;)
If you want more detail or to talk send me message.
Good luck!