There is a person that has hurt my family and me in a way that has changed our lives forever. And the other day this person was at my place of employment. I had no choice but to be professional and tried my hardest to not engage in any communication with this person; when every fiber of my being wanted to yell and scream at this person and comfront this person and make them acknowledge everything that they did wrong and force them to take responsibility for their actions. Now I have heard from other people that they did feel bad about the situation and that they had no idea that it had happened, even though I have knowledge of the fact they new this person was capable of doing what they did. But I did not say anything. I kept my mouth shut and I let this person leave without saying a word to them. It reall threw me for a loop seeing them. I definitely did not expect it and felt blindsided by the flood of emotions that have followed. I thought I had put to rest a lot of these emotions because I had to in order to be there for my family but now I am having a really hard time dealing with it and have so much regret not being able to have my chance at telling this person what the consequeces were to their actions. How do I let it go? These emotions have seemed to consume me and I am just not copping with it well.

Do you expect to have to see this person regularly? Or was this hopefully a one time deal?
Have you tried counseling? I found it helpful for learning to cope with emotions. I had a lot of issues with my mother. And she would sometimes show up unexpectedly at work. And even now if I get a surprise phone call from her it can throw me for a loop. I don't go to counseling anymore, but there's still sometimes that I need to talk so I turn to other family members that understand the situation. But it has gotten easier. Also, writing letters (I never sent them, just shoved them in a drawer until I was ready to throw them away and let go) helped a lot too. I was able to write everything I was angry and hurt over.

Allowing that person the time and effort it took to bottle up those emotions required you to have this 'pseudo' break down.

Coping and direct actions in dealing with highly emotional situations is what makes us ready for the next round, and the next,etc.

We can,be passive,allowing the situation to pass by unannounced.
We can,be aggressive,confronting them and making our points(and perhaps an arse out of ourselves in the same motion)(Handling emotional pain with emotional responses has never been a strong point of mine,things seem to turn ugly)
We can,be victims to the entire situation and play on others emotional responses until we make up our minds.

The 'new' or 'direct' approach we might take if this ever arises again.(meaning,LEARN to cope with this in a constructive manner before we make bad decisions)is what shows us and the world that we can grow from experiences,not be stunned or halted entirely from them.

You most likely did what I would have done, not knowing any of the details naturally,but if there was a fear factor,a social factor,a security factor,etc.. I think most people would do what it is you did, and feel the same 'regrets?' you are feeling?

The flood of emotions are a natural response to pent-up emotions.You are not defective,you are not abnormal or different from others.. everyone deals with stress like this in different ways, it's what was learned and not repeating it that makes us who we are.