Note this is in no way legal advice. You should hire an attorney for legal advice.
I'm assuming you already tried to negotiate with your noteholders before coming to this forum. If not, you need to do that now. If a friendly discussion did not result in a resolution, you need to hire a lawyer.
Keep in mind that you will need to pay the lawyer and any other professional fees first when you receive any payout.
More info would really be needed but here are a few ifs and buts:
I assume the notes are also secured by the full assets of the company. If so, keep in mind that the noteholders could demand their security and then make a deal with the buyer. Your reaction may be to file for a voluntary bankruptcy in which case the court will decide who gets paid what. For sure the common shareholders will still not be paid, unless they have some uncommon leverage that you have not included in your question. Whether the purchaser sticks around or becomes a debtor in possession instead is another matter.
Regardless, you will have to pay employees who are rightfully due a realistic level of wages and their benefits. This is not limitless unless your noteholders agree. Generally, unless you make a friendly agreement with your noteholders that is very employee friendly, you will fall back to the statutory wage limits (with the exception of pension type benefits which will get more generous treatment) and the 180 day limit unless you make a peaceful negotiation and do not go through bankruptcy.
Next you will have to pay your debts of $250,000.
Your secured creditor, I'm assuming due to your concerns that they must be secured, will receive the rest.
Like I said, talk to them first and see if they will agree to carve out some amount for the founders, although I think from what you've told us it is unlikely unless they are a government institution.
Then hire an attorney to help you through this process so there is nothing that comes back to bite you. But, without that friendly and generous agreement with creditors, or you owning some key intellectual property in another entity to which the noteholders have no rights, you will most likely need to put any recovery for common shareholders out of your mind.