I don't see him being able to punish you or "break you down" without your cooperation. From what you've said, the prospect of that inheritance is the biggest, perhaps the only, leverage he has on you at the moment.

If* I were dealing with someone I considered poison like that:

• If I did ever choose to resume halfway normal contact with them it would have to be on my own terms, in my own time, and only after it was entirely clear I wasn't being bribed to do so.

• I'd expect to pay dearly in advance for any inheritance I might ever get from them.

• I wouldn't count on actually seeing any of the money.

• If by some miracle I did end up with an inheritance out of the deal, I wouldn't expect to enjoy it much.

• I'd expect everyone who'd been urging me to go after the inheritance to swarm around as long the loot lasted, in the hope that I'd share more of it with them than with the other contenders.

Your mileage may vary. Good luck!

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*Like the Navy about nukes, it is my policy neither to confirm nor to deny that I am.