Help need my son to get out of cosleepinv!

Ujena • Just got married August. Expecting our first baby coming July 2015<3
My son has been sleeping great in his crib Intill 4 months he's currently 6 months now. 
He got bad congestion at 4 months and cough and my husband and I thought best to keep him with us so now he's to use to it and I can't get him back in his crib he crys so bad if I just place him in there asleep or awake!!! Help any suggestions?