feeling like a horrible mom!

Last night for the first time in 16 weeks my son fell off the bed.. I usually have him in between me and my husband (last night I was next to my mom because I'm visiting her) well last night I guess I fell asleep feeding him on my right boob which is closer to the edge. One minute I was feeding him and the next I wake up to hearing him hit the floor and a cry... he's 4 months old and I'm freaking out because he was a preemie.. my mom said he was fine because he was alert , and smiling after but I'm still freaking out. There's not even a bruise but every little thing he does now whether it's coughing or sneezing my heart starts to race.. I don't know how I'm going to tell my husband... because he's going to tell his mom and I'll never hear the end of it on how he shouldn't have been in bed with me in the first place... I really hope hes okay...