How do you reconcile someone's apology with the fact that they actually did what they're apologizing for?

A long-time friend of mine has become mentally ill due to some trauma she experienced combined with a family history of mental illness. Although we have been friends a long time, we now tend to have big arguments every few months.

The last time we had a big argument (always via text or email) she said some really mean things. I don’t argue like that – I tend to try to stick to the facts.

I am able to see her at meetings of the organization we both belong to and still be friendly to her, or talk on the phone briefly and still act friendly. She did recently apologize to me to “make it right” and so we could see each other at meetings and it not be awkward.

She’s now asking to take me out for my birthday, which is next week.

I can be friendly to her but I am having a hard time getting over the mean things she said. I don’t want to have a friendship with someone who I constantly fight with. I don’t have time or energy for drama.

How do you reconcile someone’s apology with the fact that they actually did what they’re apologizing for?