Husband Lied.....

Alright ladies, I need some advice. So my husband & I share a vehicle because I work from home. Mind you, we just purchased it in October and it was not cheap but because we just had a baby, we figured we needed something safe and reliable for her. Since we bought it though, we’ve had a lot of problems with it and it’s been back and fourth to the dealership (who have not done a great job when it comes to fixing it). We just got the vehicle back 2 days ago and I took it today to the store. As I went to open the back hatch, I saw a huge dent with paint missing. I immediately called my husband and told him to call the dealership and ask them what happened because there’s damage to the back. He told me he couldn’t believe it and he would call. I got home & took photos and told my husband I was sending them to the owner of the dealership to see what happened. He told me he was really mad about it and to let him know what the owner had to say. I texted him the pictures and asked what happened to it. After a while, my husband started acting strangely, asking me if he had answered every couple minutes and randomly saying “yeah I have no idea what happened to it”..... So I asked him if he knew of anything that could have caused it. He said no. I asked him to swear on my life he didn’t know . He then said “...well I backed into a mailbox a couple weeks ago but there was no damage”. Right then, I knew he did it. But he continued to lie to me saying “there wasn’t any damage”. I got furious and he eventually confessed that he did it. I can understand making a mistake but not only did he not tell me this happened, but he lied to me and went along with me being mad enough to text the owner of the dealership blaming them for something my husband knew he did. He’s been acting so strange lately, he’s been very short tempered and snappy and now he’s lying about stuff like this and something just doesn’t sit right with me. I’ve tried talking to him but he always feeds me these “I’m fine” lines because I can tell he just doesn’t want to talk. And now I’m furious and don’t want to talk to him about it. How should I handle this?