A thing I love about my therapist is, that I tell my anxiety stories exactly like you, without much emotion and pretty clear and to the point. Still, in that moment, I experienced heavy levels of anxiety, but I can't just reproduce that at a later time (that sounds odd to me anyway). But he takes my word for it and works through it with me. Never in my therapy did he not believe me, just because I didn't tell it with a terrified look in my face.
Yeah, that's the great thing about group therapy. It's designed to work through interpersonal things that come up with regular people who have no training and are just as concerned with their own problems as you are with yours. This was something that never came up in ten years of individual therapy. I'm not sure if my individual therapist was aware that it could be a problem, but she was the one who suggested I do group therapy, so maybe she was. I should ask her.
In my experience, they can sometime help and sometimes they can't. If they understand your issue, it can be easier and quicker to talk through your issues with a friend. Deep, buried anxiety issues are not understood by people that don't experience them. I, a completely healthy young man, constantly worrying about my heart, was met first with concern, then with dismissal as my issues didn't disappear after a week or so. You can become very annoying to friends. People who understand might be better. In my opinion, a therapist is the best, everything is inferior to that.. But that's just what worked for me.
It would be cheaper, but you'd lose your friends, unless they understand why you're talking about the same miserable repetitive shit every week, intentionally working through the worst of it, often resulting in everybody walking away feeling exhausted and dragged through a sewer, which you might inexplicably count as a success. Nobody will tolerate this unless they are really sold on the value of the process, or are miserable enough that they're willing to try anyway.
Seriously, it's so, so different, and most people in group therapy are having difficulty maintaining social connections already, because sharing emotionally icky stuff is a really hard thing to get right. Some people aren't good at recognizing boundaries and get ostracized because they overshare. Other people undershare because they aren't sure where the boundaries are or don't have the sophistication to share within boundaries without accidentally crossing the line. How to talk about your issues with various people (coworkers, family, friends) is a common frustration that gets talked about in group. No matter how progressive your social network is about whatever issue you have, people still conform to the law that if you make them feel good, you will see more of them, and if you make them feel bad, you will see less of them.
For example, one woman in my group was left by her husband after she discovered he was cheating with a woman twenty years younger than her. He had told this woman he was divorced and fathered a child with her. What her husband became widely known, and the women in her social group were, theoretically and vocally, supportive of a woman in her situation. But her social opportunities dried up overnight. Nobody was comfortable with the fact that she was miserable, that she couldn't afford to go to fancy brunches with them, that she was now selling her house and taking classes in the afternoon to get a nursing certification while they were sipping chardonnay and worry about hiring a new maid. None of them wanted to be face-to-face with a reminder that they were aging and their husbands might have a hot young sexual outlet somewhere, and that their lives could fall apart for the same reason. Some of her most loyal friends would meet her occasionally to express sympathy, but it just happened to always work out that they couldn't invite her to anything with other people. You'd be surprised how thin people's support is, and how strong their tendency is to assume that if being around you makes them feel bad, and other people don't make them feel that way, then you aren't doing what you need to do to deserve their support.
Even in intimate relationships, people don't always process why they're feeling the way they do. When someone says, "It's okay, whatever you're going through is okay, I just need to feel like you're here for me," they might not realize that they equate feeling like their partner is there for them with feeling safe and secure with their partner, and they don't feel safe and secure when their partner expresses anxiety.