ESH. Mixing family with money is always fraught.

You should have drawn up a contract with them for your protection and to ensure everyone was on the same page and there was a clear timetable to get that money.

You shouldn't have spent the money until you had it or had spoken to them first and knew it was immediately getting deposited, that's on you. You said you were in deep into your process of getting your business up and going and learned about not getting that money. During all this had you spoken your parents? Had they repeatedly said they were giving you money and all of a sudden said no or was it only after a few conversations a year ago? Those are big differences.