My soon to be two year old son had been climbing out of his bed?

so i switched his crib into a toddler bed. But now I can't keep him in it! for the first few nights, I sat next to his bed with him until he fell asleep. I don't want to be in there for an hour everynight, so I tried to sneak out before he was asleep...he freaked out! I put a baby gate up in his doorway so he couldn't get into anything dangerous and he just stands at the gate a SCREAMS for EVER! I've tried puttin him back in bed at least 10,000 times a night...and then when I'm lucky to get him asleep fast and get to sneak out, he wakes up at about 2am and screams until I pick him up. I'm too tired at 2am and tend to just put him in bed with me...I know thats bad but I don't know what else to do!!! Please help! I'm a single mom with a full time job and I need some sleep!!!