I'm curious to be honest at how long you were together "before" you got married and if you married because you were 28. If you settled and now wishing that you had cold feet a year ago.
This is taking from you.. Just because you are married it does not mean that he has the right to pick out a car that he wants, drive that car 5 days a week, create a huge monthly debt and trade in your car to get it. That's what he did right? Did you get to shop around yourself, pick something you like. No.
I don't think it's a good idea to hold onto a car that long it looses it's value but you loved it, he had to have known that. And, I think it would be different if he did this and you were the one driving it daily and you loved the new car, just an adjustment.
I think that you are upset because you feel used and now in debt when you weren't.
As advised, be assertive. Yes, sometimes things are "ours" when married but when something was yours before, you have a right to discuss and come to a mutually agreed conclusion.. I can't see anything mutual here at all.