I'm sorry you have to deal with that. That's a classic trigger situation. The bed any bed reminds you of the attack and triggers a flight or fight response.
You'll need to work with your therapist on that. If you're able to sleep well on the floor, then for now, I'd suggest to keep doing that. A better solution might be a couch or air mattress. A good night's sleep is too important to take lightly, so for now, whatever works.
Your therapist might have some better suggestions and something that is a better long-term solution. I used a futon for a number of years.
Do you know if any / all beds bring this reaction? Or maybe its a particular kind of bed or a particular type of blankets, pillows? Maybe there's something about the room. I ask this because sometimes triggers are not what they appear to be.
It's also important to consider good sleep hygiene. You can search for that on the forum or elsewhere on the internet. Good sleep hygiene might mitigate the symptoms a lot.