K.,
I have been in your shoes with a non sleeping, (at the age of 2) child and that level of exhaustion is very difficult on your health, and your ability to be a mom. I was trying all the regular advice for months on end and feeling like a failure. My son suffered from severe sleep terrors however, so I could not just let him in his room to cry if he awoke at night...he easily could have gotten hurt.
So after a good 8 months of misery, constantly being sick, mentally frazzled and at the end of my rope, I finally read somewhere to just do WHATEVER it takes for you and this child to get some good sleep for a month or 2. Sleeping with a parent will not warp a child. Most cultures do sleep with their children. Sleep 'expers' disagree, but many parents who have gone through it say it will get you both out of the sleep deficit and 're-boot' the sleep pattern. The more tired the child becomes the worse they sleep, and the harder for them to fall asleep on their own. The more tired YOU become the less patience you have. I am not a co-sleeping advocate, I had my baby in his crib the first week home,and I dislike having to sleep with a child in my bed. BUT you reach a point where something has GOT to give. So, we just bought him a big kid bed, (twin, with bed rails) and either me or my husband just slept with him. OH what pure, sweet joy it was to SLEEP again. We were all happier. And for our child, we were making progress in that he was sleeping in HIS bed and straight through the night. After a month, we would just leave after he fell asleep. Then we taught him to fall asleep while we sat in his room, humming or singing or reading to him. He's 4 now and goes to bed at 8pm by himself, sleeps straight through until 6:30/7am and all is well.
Even families that co-sleep do not have 12 yo kids in their bed. Whatever you decide to do, he will outgrow this phase. I promise. Good quality rest is so crucial to immune function, mood, growth, etc. I figured, as parents, WE don't sleep alone, isn't kind of silly to expect a child who is still in diapers to do it without fuss? With all that being said, do whatever works for YOUR family, and on that, only you are the expert, get some rest, and get your own bed back (even if it takes a bit of time).
Best wishes.