I'll start with number two: DON'T. Your money is your business. You are a vulnerable adult, your parents have been abusive towards you and they and they need money. As you probably know in your gut, disclosing to them that you've received a windfall is a BAD idea. You don't have to feel guilty about not telling them, even if you have been financially dependent on them in the past. It's none of their business. Don't count on the trust - if you end up receiving any money from it ever, you're lucky, but I've heard about a lot of abusive parents using a future inheritance or trust as a carrot to make their offspring obey, and in many cases the money wasn't actually there.
As for number one: I don't know about any legal options that you might have in the US. I know that in my country some banks offer special savings accounts for people with poor impulse control: any withdrawal from the account has to be announced 30 days prior. Another option would be to transfer your nest egg to a separate account and automatically transfer a percentage of your monthly income to that account as well, and leave the account details in a safe with a trusted person, like a solicitor. You'd have access, but you'd have to make an appointment, talk it through, etc. I would pick a professional instead of a relative for this task. There's also the option of a voluntary conservatorship, but I think that's a pretty extreme measure, which should be a last resort.