Hey Ryan. I'm not a big fan of AA, but a few of the steps actually make a lot of sense. The one about making direct amends whenever possible is one of those. However, if making amends will cause harm, the only thing you can do is accept the fact that those people don't want you to apologize or explain anything.. in those cases, the best thing to do is leave them be.
I had a similar experience with my ex girlfriend. I have tried on numerous occasions to talk to her.. not to try and win her back or get back in her life in any way, but because I genuinely want to just say "I'm so sorry for what I put you through." But now I realize that by trying to contact her, I've caused more harm than good ya know? Maybe the same situation applies with your old colleagues.
Some times, the amount of harm we do can never be taken back or amended for. That's the kind of thing an alcoholic has to live with every day for the rest of his or her life. The only way to make it better is to never let it happen again.