Apologize for the action, not the reaction
I am sorry you felt hurt quietly shifts responsibility back to your friend. Name what you did instead: shared something private, dismissed them, chose someone else, or spoke cruelly.
Specific language tells your friend that you have thought about their experience. It also prevents the apology from becoming a vague attempt to restore access to them.
Show what you understand now
A good apology includes the consequence you can now see. Perhaps they felt exposed, disposable, or unable to trust you. You do not need to dramatize it, but you should show that the lesson goes beyond I should not have done that.
Do not promise that you have changed forever. Name one concrete change you have already made or will make, then let time prove it.
- Describe your behavior plainly.
- Acknowledge the likely effect on them.
- Offer repair only if it creates no obligation.
Leave the friendship outside the bargain
An apology is valid even if the friendship never returns. Do not attach a request to be friends again or ask them to decide immediately.
If ordinary contact is unavailable, one announced, refusable request can carry the apology. If they decline it, accept that as the answer and do not search for another route.