Been saving my son's pip payments in my account but did not declare as my savings !

Hi

First time here.  Foolishly I have done something very stupid potentially. I really need some advice as been trying to get some for over a week now from various places but can't as seems a bit of a grey area to everybody I talk to, apart from the lovely man I have just spoken to on the helpline here.  even citizen's advice are not sure.

So, My son has a disability & receives pip.  I am his appointee as he is not able to manage money well.   He has received pip payments for over 3 years & before that received DLA.   I personally receive Housing benefit & I have never declared to housing benefit the savings from my sons Pip, only my own savings in my current account.  The savings for the pip payments are in a separate savings account but in my name ! Stupid , I know looking back in hindsight, what I should have done was opened an account in my son's name but my bank had offered me this savings account with a very good interest rate, better than other accounts with other banks I had seen so I opened it & have been paying a regular payment into that account each month plus others sums of money at different times over the past 5 years that has not been spent from the pip each month as well as the remainder of the DLA he got previous to that. 

Last week I had a conversation with Housing benefit & mentioned this other money for my son, voluntarily, this is when the problems started.   They said I should have declared this to them.   I honestly didn't think I had to as the pip payments were in my sons name just going into my account.   They have said they will most likely class this as my savings that has not been declared but said they would go away & investigate, but need time.  That was over a week ago.   Since then I have not stopped worrying , I feel sick & can' eat or sleep properly.   I am so worried I have done something that will now be classed as benefit fraud .   I am an idiot & in hindsight looking back I should have opened a separate account in  my sons name.   Obviously there could be a massive overpayment now as the money saved in that account was £24,000.   The money is still there so it has not been spent , well a few thousand has.   If I have to pay it back, I accept that as is my mistake, all be it a very stupid one.   I did not see the point of spending all his pip money for the sake of it & wanted him to have something to help him out later in adult life if he should ever be able to live independently.   Its not the fact of paying it back that scares me the most, its the fact they may punish me & give me a prison sentence for benefit fraud.   My son can not cope without me & I am his sole carer.   It would be  just awful for him not to mention my daughter who also has the same disability & is in specialist provision if, I was taken away from them both.  Am I overthinking this ? 

As I said I have just spoken to a really helpful man on the help line who has put my mind at ease slightly about telling me about housing benefit regulations .   I guess I am just looking for some more advice from other people that may have some understanding of this situation or been in this situation themselves ? 

Sorry for the long post & thank you for taking the time to read it.   Any advice greatly appreciated.