How can I hide panic attacks

If you read my question from a couple days ago, you'll know that I had to go out with my friend for ice cream last night. Being a total freak of nature, I absolutely cannot eat in front of people, especially this guy. So I ended up making this hugely secret plan to have one of my girl friends come along (she's friends with him too, so it's cool) so that I would be less anxious. It didn't work.

Well, it worked a little, but while we were eating, I could feel myself having a panic attack. She noticed, but the guy didn't, which is lucky, but I think he knew something was up and just didn't say anything. I can't predict when these things happen, so how can I hide them best when they occur?

Update:

This guy is so nice that it's hard to describe. He doesn't have a judgemental bone in his body. He's incredibly understanding and open-minded and he only wants what's best for his fellow man. He wouldn't hurt a fly.

But I think that's what scares me about him - I'm so used to being treated like crap by guys that being treated nicely is intimidating..