11 month old sleeping pattern changed abruptly, won't sleep until after 2 am!!?

[Daisy]

We had our son in a great pattern. Both our boys got a bath at 8:30, story time at 8:45, then our 3 year old had lights out, and our 11 month old was nursed and put down. We cosleep with him, and have since he was born. Usually I nurse him on my side and he falls asleep while nursing. This has worked well for us for the past 11 months. Now suddenly, he goes to sleep at 9 and then wakes up around 10:30-11 as if from a nap, and refuses to go back to sleep until 2 or later in the am. We keep the lights out and no TV, no playing, no engaging him. I turn my back to him and he stays between me and my husband. The problem is that he cries and starts to hit my husband and I. My husband has to wake up for work at 5:30, so it isn't possible for me to continue this as he is waking my husband up throughout the night and he is now exhausted every morning. We are buying a crib for him tomorrow, but I am not a "let him cry it out" mom. I have never been able to do that, and can't. So how can I either get my son back on his normal sleep pattern, or how can I move him from a cosleeping bed to a crib as gently as possible? Also, he is cutting a tooth at the moment, so I realize it could be causing his weird sleep, but my oldest son gets up between 7-8 and this 5 hours or less of sleep is making me a grouchy mom, and it's not fair to anyone. Any advice please???