Marriage advice...

Danielle
My husband and I were out earlier today in his car... He opened his center console looking for his sunglasses cleaner, and I noticed a handwritten note from me to him in there. I went to reach into the center console and he awkwardly pushed my arm away and shut the console quickly. INSTANT RED FLAG. I asked what the letter was and he just said "just something you wrote me", but of course my hormonal, pregnant mind was spinning with reasons why he pushed me out of the console. Fast forward a few hours, he was cleaning our basement and I went to his car to investigate (because I'm totally not psycho, lol)... I was literally expecting to find condoms or something sketchy, but found nothing suspicious. I then picked up the letter I wrote and read it... I don't even remember writing it, but it wasn't a cute little love letter. We hit a pretty rough patch about a year and a half ago, one I was afraid we wouldn't make it through, and I guess I had written him a letter in the midst of it. While it was an honest note expressing my concerns and emotions, it wasn't something I was happy to find in his car :(. It made me sad!! Like, how often does he reread that? How often does he rehash that bad time in our relationship? 
How would you handle the situation? Reading that letter made me want to write him a whole new long letter about how much I love and appreciate him. But I really want to take that letter out of his car! I just could not imagine in the future getting into an argument or something, and then him finding that letter and just getting more upset and mentally going back to that dark place :(.