Sleep training 13 m/o

my 13 month old was sleeping in his crib for about 6-7 hour.   Then we had two teeth come in and that was thrown out the window.   We have tried other sleep methods. But he would flip out the second in his crib.  Two nights ago we put him in his crib.  And let him cry.   We went in 2 - 3 times with in 2 hours.  That just seemed to make it worse. But he finally fell asleep.  Last night I put him to bed and in 25 min he was asleep.  Tonight it was only 10 min.     My only concern is - we are not going on to reassure him when and if he does wake up.  We wait a min or two and he has fallen back to sleep.   I’m the crazy new mom - am I hurting him emotionally but just leaving him all night?!