The first text has one job: lower the threat level. It is not the place to win the case, explain your side in full, or extract an apology. Every sentence should make it easier for your partner's nervous system to come back to the table, not harder.
Three parts, in any order. Accountability: one specific thing you own. Care: a clear signal that the relationship is not in question. A next step: a concrete time or plan to actually talk. If a draft contains blame, sarcasm, or a tally of who did what, it will restart the fight wearing an apology costume.
