Bad day

Today was my first really bad experience since I have returned to the interpreting world. A client was already upset and mentioning a lawyer when I didn't understand a word, granted a basic word, but one I haven't used or seen in a while, and I had a freaking brain freeze. So then the client asked if I was certified and claimed that the communication wasn't good in the situation and was definitely going to get a lawyer. I know that I did a good job, everyone needs a bit of a nudge on a word here or there, this client was just pissed and took it out on me as well as who they were really mad at, but I still feel like crap on toast. Blech, and it is pouring out.