The adoration of Mommy is normal. But that doesn't mean you should feed into his dependence on you. The two do not have to be intertwined. Are you still feeding him? That should stop, cold turkey. There is no reason to still be feeding a 3 year old who is capable. If he fusses and then you just feed him, that will teach him that he can get his way by fussing. If he gets upset because your husband puts him into/takes him out of the carseat and so you take over, again you are both teaching him that if he gets upset, he gets his way. That is a sure recipe for a spoiled brat.
He is old enough to understand about rewards. At 3, my son was getting stickers on the calendar or "milk shake points" (beads in a jar). We had certain criteria and a pre-set reward (Star Wars Legos for bigger goals, milkshake at the local burger joint for smaller goals in our house) when he had a set number of beads or stickers. We used this technique for potty training, staying in his own bed at night, keeping his room clean. You could do it for feeding himself, climbing into/out of his own car seat, getting himself dressed, whatever indepence goals you set for him.
If I were you, I would go away for a weekend or longer if you can. Volunteer to go on the business trip, or stay with a girlfriend or go visit family. Give your son some extended time with your husband. If it works for your husband's schedule, have him start dropping him off or picking him up from school on a regular basis. Encourage him to be independent and heap on the praise about how proud you are of him doing so much for himself. If you have a second baby and you still do everything for and coddle kiddo#1, his demands will only get worse as #2 sucks up all your time and energy.