My 3 year old wont go to sleep without me & wont sleep the whole night

you started an awful habit, that now has to be broken. put your child in a toddler bed, and tell him/her to stay there. create a bedtime routine such as, bath, pj's, brush teeth, read story. sit on the bed while you read a bedtime book, and when your done, leave them room. tell the child he/she is not to get up, unless for the bathroom. put a gate in front of the bedroom door, even, to keep him in the room, atleast. stop putting him in your bed, NOW. it's only going to get better over time, when you offer him no other options, and stick with it. don't give in when he/she throws a fit.