This has happened to me as well. In fact, about a month ago, we left MC and i cried the whole way home and just ripped my WH a new one.
The thing about MC (for me anyways) is that we are talking about all the wrong.....what is broken and needs to be fixed. That's painful shit right there. Its HARD to look at yourself and see the flaws...its hard to look at your partner and see the flaws. And it totally sucks knowing you have to go to MC because someone cheated. Then you get pissed off. Its quite the roller coaster.
For me, i feel that MC is working because of the following...
i tend to leave MC in a better place more often than not. Yes, I am very sad and upset many times when i leave...but after i have had some time to process what we have talked about, and i step back and look at the bigger picture, i know i am stronger and much better off now. The sad and upset feeling generally doesn't last but for the day...and i am usually ready to face my week.
I really do like my MC and while the work we do is very hard....i know it is work that needs to be done. It is sad, and it is difficult...but in the end i know i am better off.