DP and I live in a big city in a very central location. There’s no off-street parking and finding a spot at all is often difficult, so we regularly end up parking several streets away from our apartment.
When we got together ten years ago we both had our own cars which we sold a few years later and went on to buy just one (used but very nice) car. It’s his car, he paid for the lions share and I only chipped in a few thousand. We agreed to share the car (otherwise I would have refused to sell mine in the first place) but it only gets used about twice a week and I probably drive it more than he does as I do more of the grocery shopping, etc.
When DP came home from work earlier he happened to walk past the car and noticed some pretty ugly damage to the front bumper. He was understandably really annoyed and asked me if I had noticed anything this morning when I last used the car. I hadn’t but said that I couldn’t be sure as I was in a bit of a hurry and might have missed it. We had a bit of a moan about the shitty parking situation (we’ve had several incidents where people caused damage but didn’t leave a note) but apparently I wasn’t interested / outraged enough and too quiet which is apparently ’suspicious’. He now says it could easily have been me who damaged the car (it absolutely wasn’t, I am very careful) and that ’we both know I wouldn’t admit to it anyways’ if that was the case. I feel so so hurt by this assertion to the point where I’m tempted to call it quits on an otherwise pretty happy ten year relationship. It’s an incredibly unfair thing to say and I wonder how we can go on (planning on TTC next year) if he has such a low opinion of me. Am I overreacting? The whole thing has turned into a massive argument but he's refusing to apologize and standing by his comments. 
So as not to drip-feed, the reason why I was less bothered by the damage than I would normally be was that someone had already driven into the front bumper earlier this year and their insurance has already paid out for a new bumper. We hadn’t got round to getting it changed yet (damage was internal and not very visible from the outside), so I felt that we were ’lucky’ there timing wise.
Oh, and please don’t jump on my SPAG, English is not my first language.