Hi Gail,
I think it might depend on what decent relationship means to you. If it's mostly calm, and if since you see her only a couple times a year you can keep it that way, I do understand the wish not to breach the peace. Or, are you in a lot of present-tense pain whenever you're around her or speak to her? In that case, it might be worth trying to talk to her about it, or ask for another apology if you think she's capable of giving it.
Or do you feel mostly at peace around her now, and it's just when you're on-your-own dealing with the memories that the hard pain comes up? If that, then maybe it's like you're healing in a parallel universe from hers, and you might not need her acknowledgment of your pain in order to keep making progress with the healing.
I'm not sure this is helpful, but for what it's worth.
Hopalong