But we're 4 months in with not much sign of change, nor of either of us accepting the other person's interpretation.
Here's the thing- you and I can debate literally any of the tough topics in the world right now (politics, religion, war in Israel, border crossings, COVID, etc) and there's a decent chance we wouldn't agree on everything. Could we still build a relationship though?
Of course we could, as long as the thing we disagreed on isn't the basis of our relationship.
Right now, the basis of your marriage is arguing over who said or did what in the past. Why does that remotely matter though? Why are you wasting energy trying to say "I'm right" or "You're wrong" with the person you love? What could you possibly gain from that other than a divorce?
It's like that old movie WarGames about nuclear war- the only way to win is not to play.
Look, I was married to a BPD wife for 25 years...and we had a BPD daughter. I completely get it. Just last week, my ex brought up something that happened 24 years ago, and her "recollection" was that it was 100% my fault and she was the victim. That's not what happened at all, and we are divorced now. So what's the point in fighting over that? I simply told her that we both shared blame and I'm truly sorry for what happened.
And she was silent- what could she say? That thing hurt her enough to carry it for 24 years, so I apologized for my part. In other words, I validated the valid, while lightly pointing out the invalid. Just one quick, simple sentence filled with remorse and empathy. I wasn't going to play the game, so I let her "win".
I didn't get an apology for her part in the argument 24 years ago, but I didn't need that either. The simple truth is that I let that go 24 years ago like a typical spouse who's not mentally ill. I did my part for her, to let her heal and let go, and our conversations the next several days were very different. She wasn't on edge as much and she showed me more empathy for some things I'm dealing with. So in a way, I "won" as well by choosing not to play the blame game.
You don't have to accept your wife's interpretation to fix things. Instead, you need to stop playing the game entirely and get back to simply loving her. That allows her to re-center and get back to loving you as well. You're the "mentally stable" one here though and that means you have to take the lead.