Finances and relationships

Hey, three years ago I co-signed a lease for my boyfriend. I few months after I got a lease of my own. About a year into his lease he could not longer afford it due to job changes. The car was repped. Now my lease is up and time for me to get a new one. While we are at the dealer he was asking if there was anything they could do for him. He has a four year old truck with a lot of miles that he pays over $500 a month for. But he would only want the sport car from them, bc its Kia and doesn't like anything else they have. Well I got approved for my lease and apparently approved me for the car he was inquiring about. Meanwhile no one ever said that's what they were doing. So when I called to ask about my car, they kept saying I was picking up two cars. Anyway this got my fiance thinking i can help him get the car again. I said no, last time i learned my lesson. Plus I dont think this car is a smart choice, we have a child. One of us should have a bigger car. It even turns out it would just be me leasing the car, not co-signing. Well ever since I said no. He's been giving me nothing but grief. Acting mad at me and saying things like I dont care about him, saying his car is going to break down. We are getting married on December. I really dont want this resentment hanging over us But I dont think I should have to finance a car for him. Am I wrong?