Hi A.,
There is nothing in your post that leads me to believe that you owe anyone an apology for YOUR divorce. Come on, girl! They didn't suffer through a failed marriage, you did! The only thing that I might apologize for is that you didn't remain in contact or didn't keep the friendship going. But in all honesty, did they put the effort out, either?
Anyway, I understand the draw to link up with old friends that you were particularly close to. I've reconnected w/ my high school girlfriends through FB and it's been absolutely wonderful. A good 20 years had passed before we reconnected and it's been such a great thing to "be" in one another's lives again, even if it's only through the internet, as some live in other states.
One of these ladies was my best friend in high school and we were tighter than tight. We had a falling out our senior year, tried reconnecting in college and it fell flat, but we were able to reconcile through, yes, FB. She was always in my heart during our 20 years apart and I honestly thought of her often and really, really rued the fact that we were no longer friends. I had no way of getting in contact with her, but finally found her through FB when I signed up. I had some apologizing to do and I jumped at the chance to do so and we are now closer than ever. Even though two decades passed, it's like they never did when we are together. Know what I mean?
So I say, reach out, say hello, say you've missed them all these years and would love to catch up. Don't expect anything, but you never know what may happen. Some friendships are meant to last a lifetime; even if there is a pause in there at some point. Good luck!