nothing, unless you get caught :-)
You get a ticket.
As long as she has the correct insurance that allows the car to lent to a friend then it should cover you.
As long as you have a license. The insurance follows the vehicle, not the driver.
If you have car insurance ,police will never stop you even if you dont have driving license.
It all depends on her insurance cover
The speeding ticket is a separate issue. If you don't have insurance you get done for driving without insurance, speeding or not.
If the car you are driving is insured then you are not driving without insurance.
If the vehicle has insurance it will cover damage to the other vehicle but not the one you are driving. Now if you have insurance on another vehicle your insurance will cover the damage to the vehicle that you where driving even though it is not on your policy.
If your child has a license the insurance on the car will probably cover it. The company can take the position that they were not supposed to be driving it and are not covered in which case it would come back to you because the child is underage.
You would call the insurance company of the person's car that you are driving. The insurance follows the car and not the insured.
Her insurance may state 'other drivers with the insured's permission' in which case her insurance would at least in part cover damage to other people/cars, but probably not to her own car. If her insurance does not have that clause, you are probably in trouble.
You will be charged with property damage and driving without a license and most likely driving without insurance. Not good.