Children take comfort in routines. Once you have a routine settled, trade the blanket for something new every day.
Say he drags it to the table for breakfast tell him he has a choice, put the blanket back on his bed and get a toy to play with at breakfast or you'll take the blanket back to his bed and he can eat without any fun. Then when there are times that he isn't playing with it or doesn't have it attached to him then kiss him and take it back to his bed and tuck it in on top. When you see him with it offer him a new car if he takes the blanket back to his bed. One day you can offer him a rug that has roads for his cars if you can put the blanket away, stuffed in the linen closet away. Or it can go in the washer and stay there all day cause it's wet.
It will take some time but he will eventually get over it. Tell your husband that if he wants the boy to go cold turkey then your husband will need to be the one that stays with him 24/7 until he gets through the dt's, you'll be napping afterall you're pregnant and hormonal. Plus this would be the ultimate leverage if you want your husband to give up something like drinking or smoking. You could say that the child is addicted because dad is addicted. You're not going to force either one of them to quit an addiction but HE needs to set a good example.