Apologize like a period, not a comma. No “but,” no “if,” just the part where you were wrong.

Adding a condition to an apology turns it into a negotiation. The word but reaches back and cancels the sentence in front of it, and the other person hears only the second half. What they needed was for you to stop, name the thing, and let it stand there undefended. Anything bolted onto the end reads as an argument in borrowed clothes.

Write the short version before you say it: what you did, that it was wrong, nothing after. If context matters, it can be a separate conversation tomorrow. Today, let the apology be the whole message.