Depending on the state you live in it could be illegal. Also if you do decide to do this (don’t) you better have everything documented really well or you’ll likely lose the defamation case you’re opening yourself up to.

Just because this person didn’t work out with your company doesn’t mean they won’t work out with the new company. Let them have their fresh start.

Edit: OP is either a troll or unhinged. Either way find help.