Re: Regret from a few years ago
You already sent emails apologizing and got no response. So, at this point, let sleeping dogs lie---let it go.
I have to ask---how did YOU ruin the friendship between F2 and F3? I've read and re-read what you wrote and don't see how the end of their friendship was all your fault...? Did you just assume it was all your fault or did one of them tell you it was all your fault? If it is the former, that's a very big assumption to make. If it is the latter, then their friendship couldn't have been very strong to begin with.
I think that you are being too hard on yourself. When you have poor self-confidence and poor self-esteem, there is a tendency to blame yourself for things that aren't your fault at all.
So, just move on and don't be so hard on yourself. Also, in the future, don't get involved with co-workers. If you do, when things go south, it could make for an uncomfortable work environment---but I'm sure you've figured out all that by now.
Best of luck to you.