In a world where taking responsibility for your actions is a rarity - that's not an elementary question.
How does one make amends? Well - that depends.
Sometimes you can't.
Sometimes a simple, geniune "My actions hurt you and I'm sorry" is all that it takes.
It's a concept that's not taught to children - and unless you learn it as an adult - its difficult to put into practice.
It sounds as though its not so much an amends, as a trust issue in your case. Do you trust them not to hurt you again? Do you believe their apology is heartfelt? Or do you think its a matter "I'm sorry, but I'm only saying it because you expect it"?
For me - usually a genuine apology, without excuses, is enough for me to feel like the matter is settled. It rarely happens though.