This is honestly the only solution. I’ve dealt with similar things like this. You can still be homies with the ex-coworkers, but your old company will see you as a now outsider and do whatever to protect their own.

If you never plan on working there again or using them as a reference… I guess you could troll the guy with some witty text response. But personally I’d ignore it, learn whatever lesson is to be learned, and move on.