This is obviously an emotive topic.
OP - I have been where you are...my first child nearly broke me! I was exhausted, emotional and my DD was poorly rested. She would not let me put her down, I could not sit, I could not stand still...I had to rock and walk to make her sleep. I had to ever so gently put her into bed, most of the time she would wake and the cycle started again. On repeat all night for months on end. Co - sleeping and bfing to sleep didn't work. She cried til she vomited if I left her
In the end I went with her to sleep school (Ngala in WA - govt run) and learned the sleep method as described by VP above. It was fairly gentle with quite short periods of crying and lots of shush/patting. Within a week she was only waking once or twice a night for BF and went back to sleep with the same method. Honestly it is the best thing I ever did! Life changing! I used the same method ( but much earlier and no crying) with my DS1 and DS2 and they have been beautiful sleepers from the beginning.