Just trying to understand your situation.
So you had an appointment with your therapist scheduled for the near future, but based on something you said, she cancelled it and recommended you check yourself into a hospital? I'm also gathering that your physical health is fine, i.e. you didn't just attempt to CTB?
I don't know the details of the sectioning process, (I've never been sectioned) so I'm not sure how long it takes to file the paperwork and get you forcibly committed. But if it's only been an hour or two, it's possible this is what is happening to you. Hopefully someone else knows more and can fill in.
Regardless, based on what I've researched and also what I've read on SaSu, you should avoid being involuntarily committed if you can. Most people who have that happen say it is a miserable experience and not helpful at all. It's often traumatizing and really expensive too. It can also affect your employment options in the future. I dunno, maybe you know all this already so sorry if I'm sounding preachy.
If you aren't seriously trying to CTB and you want to live, I would definitely take action, just not in the form of trying to get involuntarily committed. You can tell your therapist that you are feeling better, and that you aren't in a crisis (even if that's a bit of a lie), and that you want to keep doing therapy. You can talk to someone who isn't going to freak out/panic. If you have any of the herbs mentioned in the recovery section of the forum, you could take them. Apparently some of them are really good at mitigating crises of depression, anxiety, etc. You can even voluntarily check yourself into a hospital which has different ramifications, is less expensive, is less forceful, doesn't affect future employment as much, etc.