Should I, a 34-year-old woman, write a letter to my boyfriend, who is 32, regarding our recent argument?

I'm using a throwaway account because my boyfriend is aware of my main one. I’ll keep this brief, but feel free to ask if you need more details! On Monday night, my boyfriend (32M) and I (34F) had an argument that lasted until 2 AM. We both crossed some lines, and when we hung up, I felt like the issue still lingered. He had gone out with friends the night before, didn’t sleep well Sunday night, and our argument kept him from resting on Monday, making him really tired on Tuesday. We barely spoke, and I decided to give him some space. Throughout yesterday, we didn’t communicate much (he didn’t text me, which made me think he wanted to keep his distance), but I did send a message to confirm our plans for tonight (Thursday). I felt pretty down yesterday but didn’t want to spark another argument since he seemed to be acting somewhat normally. Just to clarify, our fight wasn’t about anything he did with his friends. He did something reminiscent of my ex, which I tried to discuss with him, but his response of "I didn't think about it" triggered me even more. We’ve been together for about 11 months. We have a tendency to argue in a way that leaves things unresolved, which is why Monday's disagreement felt particularly intense— I've never felt closure after our fights, and it builds up over time. So, I decided to write him a letter apologizing for my reaction and explaining why what he did upset me. I also asked him to acknowledge that he understands my feelings and requested that he avoid similar behavior in the future. My question is: should I send him the letter? If so, when? We have a nice date planned for tonight, and I don’t want to ruin it by bringing this up again. At the same time, I fear that not sending the letter will leave this fight unresolved like the others we've had. Thanks for your input!