it's not your bed that is destroying your skeleton. Maybe if you have a shitty mattress, you should have a firm one with a latex topper, but what's actually crushing your body is that your muscles are weak and unable to support your body while you are sleeping.
picrel will fix your shit in a month if you start doing 3x10 sets every day.
You can get a roman chair for less than $100 on Amazon. If you are too weak to do this you can start with planks on your knees -> planks from your toes -> roman chair.