girls. i need advice about my mom.

so im 19 i have a almost 12 month old. the bio dad isnt in the pic, but my bf is, pretty much hes dad. anyways, we live with my mom and dad. me and my bf have been wanting to start teaching my son to sleep in his crib. hes always slept by me so its hard to put him in the crib and listen to him cry himself to sleep. sometimes it takes 5 minutes sometimes it takes 30 minutes. either way 99.99% of the time he is crying when i put him in the crib (this is for naps) my mom told me that she never did that to me and my siblings and i shouldnt do it to him, because its mean, & she doesnt wanna hear him cry for more than 30 mins. and its not like i dont go in there after like 15 minutes of him crying to try to calm him down then walk again and then hes ok after that usually. but he wont let me rock him to sleep anymore, so my only choice is to let him self cry asleep, am i being mean to him? what should i do? i wanna move out so badly. i told my mom that hes fine hes been doing it pretty good for the past week and that im his mom and this is how im going to raise him. and then she said that she thinks its funny that i wasnt like this until i met my bf. which isnt true, i was eventually going to do it with or without a bf. so im not sure. its hard to put him in his crib for a nap and then get told im being a mean mom for making him cry himself to sleep and it hurts because i love my son. i would rock him to sleep for the rest of my life if he would let me ..