C.K.
Hi, I was in a very similar situation. My 16 month old LOVED to nurse, he was never happier than when nursing, was gripped with joy and excitement when he saw the breast coming. The pre-bed feed was our last remaining feed, as it made him go to sleep in a very blissful fashion. So I thought I was never going to get him to quit it... the few times we had tried other ways of getting him to sleep they had simply failed, and he would stay up till the early hours of the morning. At first, he had a tantrum when I tried to rock him to sleep with out nursing him, so I gave in, but after a while/few days I plucked up courage and stuck it out, and rocked him for ages until he went to sleep, and finally he did. After a few nights he didn't ask for it anymore, I was surprised how quickly he forgot about it actually. A few days later one of my breasts got a bit sore because of build-up, so I let him nurse in the middle of the night, but because he was half-asleep he didn't remember the next night, and he still didn't ask for it anymore. I was nearly dried up, so I know he was mostly doing it for comfort not the milk, and in fact it started to hurt as he was sucking so hard on empty breasts. I think he gave up the fight more easily as he realised the milk had mostly gone. I offered a bottle of cow's milk instead, and he quickly switched to that at night instead, and now it has a very similar effect to the pre-bed nursing session. I felt sad when I stopped this last feed, it was such a precious time between us, but you have to consider that sooner or later this day comes when nursing is over (that weaning has to happen one day)...
Good luck! You can know you did your best for him and have given him the best start in life.