He already weaponized your previous therapy to undercut you and not trust your feelings. Now he's using the knowledge he gained about where you're vulnerable from that to undercut your decision to have him move out.
Horrible messages are such a strange tactic to try to lure an ex back in. Who enjoys reading that kind of bullshit. I think he's caught on that you're not letting him back in and this is part of his acting out. He's trying to guilt trip you and attack your mental health that he did nothing to support while he lived with you.
Since he's really stepped over the line here, I'd be really inclined to send something like this. He needs to stop sending you horrible messages and get his stuff.
Dear Dude,
You're right, I'm a horrible person for asking you and your kids to leave my clean, comfortable, roomy home that you paid no rent into and the cleaner that I paid for to clean it after you and your kids trashed it every other week. Bullet dodged. Today is your lucky day, go buy a lottery ticket. 👍
Pithy
PS: I will make a 6 hour window available for you or your movers to remove the rest of your belongings on dates x, x, or x. Your things need to be removed by date x. Thank you for your attention to this matter.
Adding, The tone of your posts from your first thread to now are so different. You sounded ground down, like you were at the end of your rope, and couldn't see an end in sight, almost despairing. Now you sound more upbeat and you get excited about things.