Go on a trip and rely on your DH! Here's what I did.
Starting in September I decided, no more morning session. She was nursing 3-4 times a day at this point - once in the morning and then before nap and bedtime. So DH was the one to go to her in the mornings and offer her food. Basically distract her. After a few weeks, she didn't ask to nurse in the morning.
Then in October, I went out of town for 4 days so DD had no access at all (she was 18 months old). I didn't leave any pumped milk either. She did fine while I was gone. When I got back, she was fine without nursing as long as I wasn't around. But of course, DH had to go back to work so I was stuck with nap time. I had planned to use the trip to go cold turkey, but I caved and let her have that one nursing session back. DH was still on bedtime duty though.
Then at 19 months, DH was off for four days in a row for Thanksgiving. She didn't ask to nurse once the whole four days (DH put her down for naps and bedtime). And that was it. I haven't nursed since the day before Thanksgiving.
The key for me was getting out of town and having DH go to her at the times she would have been nursing. DH still does bedtime now, though I can when necessary, without nursing. I consider it a fair trade though since I was the only one who could put her down for so long.
ETA: Sorry, I didn't realize he was still nursing during the night, but I think my advice might still be useful? I hope.