I remember the first time I attended a critique group. It was at the back of a Borders on 104th in Thornton. I had been careful (obsessively so) to follow the groups exacting instructions on formatting, printing, font and page count.
That night was the first time I shared any of my writing with anyone (I didn't even let my husband read my stuff back then).
On the drive there, my body shook. My legs felt like water and my stomach rolled over again and again. Maybe I wouldn't have the opportunity to read my pages--that would probably be for the best. Yes, surely there could be the chance that we would run out of time--I could make sure I was last--and I wouldn't have to read today. Maybe next time.
But there was plenty of time.
I did read, voice shaking, eyes darting frequently to the smattering of Border's customers browsing the Writing section we were camped in front of (oh God, were they listening?)
Then, thankfully, mercifully, I came to the end of my allotted 1200 words. I came to end and prepared myself to listen (silently as per their explicit instructions on how to accept critique) to what they had to say.
They said a lot. Some of it was dead on (and no, not just the good stuff.) Some of it was not helpful. And some of it I would need to think about when I had a moment to process what they were trying to get at. Like every other person who subjects themselves to this, the praise made me feel like I could fly and the criticism made cringe. Silently.
That's the hardest part about going through critique...you have to, at least outwardly, be open and accepting of it. The list of rules they provided me were valuable and I still use them--even when my agent and I were going back and forth with edits before submission. I don't think you should try to explain the parts someone is having difficulty with, especially in the middle of their suggestions. I don't think you should ever get, outwardly, defensive. I've seen this happen in the middle of a critique and it's just not a pretty sight. Come with your game face on. Sure, you're probably roiling inside but these people have taken time out of their lives to read your stuff, listen to what they have to say about it. After all, you did come here of your own accord and ask for it.
Now, having said all that, I don't think you should feel you have to listen to everything. For me it eventually became a gut instinct sort of thing. I always consider every piece of critique. Some of it I know right away is not very good advice. But some of it, some of it is like WOW! You are soooo right! Thank you, thank you. Also, if multiple people are having the same problem--auto fix for me. There's just no point in arguing the majority.