Aw, it is really hard huh?
Ella was about the same age when we started it with her.
It took 3 nights of re-settling before she slept through, but since then she has been a wonderful sleeper, only waking if she is sick or had a bad dream.
First night she cried for 3 hours on and off, second for 1.5 and third about 15 minutes. She was always her happy self in the mornings so not emotionally scarred by the experience as I worried she would be
All I can suggest is stick with it and be consistent, it take 3 days to change a habit (which was true for us) and sometimes it needs to be replaced with a new one. I started giving Ella her cuddly instead of her bottle.
Hang in there, it can be done and you won't look back once these hard few nights are over.